Tucson State University offers two MBA programs. In the first program, the students meet two
nights per week at the university\'s main campus in downtown Tucson. In the second program,
students only communicate online with the instructor. The director of the MBA experience at
Tucson wishes to compare the number of hours studied last week by the two groups of students.
A sample of 10 on-campus students and 12 online students revealed the following information.
Campus
28,
16,
42,
29,
31,
22,
50,
42,
23,
25
Online
26,
42,
65,
38,
29,
32,
59,
42,
27,
41,
46,
18
What is the Wilcoxon rank-sum test value, at the .05 significance level?(Round your answer to 2
decimal places.)
Tucson State University offers two MBA programs. In the first program, the students meet two
nights per week at the university\'s main campus in downtown Tucson. In the second program,
students only communicate online with the instructor. The director of the MBA experience at
Tucson wishes to compare the number of hours studied last week by the two groups of students.
A sample of 10 on-campus students and 12 online students revealed the following information.
Solution
Top of Form
Bottom of Form
Subchapter 12a.
The Wilcoxon Signed-Rank Test
In Subchapter 11a we examined a non-parametric alternative to the t-test for independent
samples. We now turn to consider a somewhat analogous alternative to the t-test for correlated
samples. As indicated in the main body of Chapter 12, the correlated-samples t-test makes
certain assumptions and can be meaningfully applied only insofar as these assumptions are met.
Namely,
Here again, it is not simply a question of good manners or good taste. If there is one or more of
these assumptions that we cannot reasonably suppose to be satisfied, then the t-test for correlated
samples cannot be legitimately applied.
Of all the correlated-samples situations that run afoul of these assumptions, I expect the most
common are those in which the scale of measurement for XA and XB cannot be assumed to have
the properties of an equal-interval scale. The most obvious example would be the case in which
the measures for XA and XB derive from some sort of rating scale. In any event, when the data
within two correlated samples fail to meet one or another of the assumptions of the t-test, an
appropriate non-parametric alternative can often be found in the Wilcoxon Signed-Rank Test.
To illustrate, suppose that 16 students in an introductory statistics course are presented with a
number of questions (of the sort you encountered in Chapters 5 and 6) concerning basic
probabilities. In each instance, the question takes the form \"What is the probability of such-and-
such?\" However, the students are not allowed to perform calculations. Their answers must be
immediate, based only on their raw intuitions. They are instructed to frame each answer in terms
of a zero to 100 percent rating scale, with 0% corresponding to P=0.0, 27% corresponding to
P=.27, and so forth. They ar.
Illustrate the nature of bivariate data;
Construct a scatter plot;
Describe shapes (form), trend (direction), and variation (strength) based on the scatter plot; and
Estimate strength of association between the variables based on a scatter plot.
Visit the website for other Services: https://cristinamontenegro92.wixsite.com/onevs
This presentation covered the following topics:
1. Definition of Correlation and Regression
2. Meaning of Correlation and Regression
3. Types of Correlation and Regression
4. Karl Pearson's methods of correlation
5. Bivariate Grouped data method
6. Spearman's Rank correlation Method
7. Scattered diagram method
8. Interpretation of correlation coefficient
9. Lines of Regression
10. regression Equations
11. Difference between correlation and regression
12. Related examples
Illustrate the nature of bivariate data;
Construct a scatter plot;
Describe shapes (form), trend (direction), and variation (strength) based on the scatter plot; and
Estimate strength of association between the variables based on a scatter plot.
Visit the website for other Services: https://cristinamontenegro92.wixsite.com/onevs
This presentation covered the following topics:
1. Definition of Correlation and Regression
2. Meaning of Correlation and Regression
3. Types of Correlation and Regression
4. Karl Pearson's methods of correlation
5. Bivariate Grouped data method
6. Spearman's Rank correlation Method
7. Scattered diagram method
8. Interpretation of correlation coefficient
9. Lines of Regression
10. regression Equations
11. Difference between correlation and regression
12. Related examples
1Bivariate RegressionStraight Lines¾ Simple way to.docxaulasnilda
1
Bivariate Regression
Straight Lines
¾ Simple way to describe a relationship
¾ Remember the equation for a straight line?
z y = mx + b
¾ What is m? What is b?
¾ How do you compute the equation?
(x1,y1)
(x2,y2)
What if every point is
not on the line?
¾ Straight line may be good description even
if not all points are on the line
Computing the line
when points are scattered
¾ = a + bX
¾ Y-hat means predicted value of Y
¾ Computing the slope:
¾ b = 𝑋−𝑋 𝑌−𝑌
𝑋−𝑋
¾ I ill ri e/r n, b no e al o
consider variability in X and Y
Computing the intercept
¾ a = - bX
¾ Need o pl g in al e of (X, )
¾ Can e j an Y or X!
z Line would be very different depending on
which ones you chose
¾ Must have X and Y that we know are on
the line
z mean of X and mean of Y
2
Computing the intercept
¾ Regression line will always go through the
mean of X and mean of Y
¾ A = 𝑌 - b𝑋
¾ Le r it with our example from before
X
(# of kids)
Y
(hours of
housework) 𝑋 𝑋 𝑌 𝑌 𝑋 𝑋 𝑌 𝑌 𝑋 𝑋
1 1 -1.75 -2.5 4.375 3.063
1 2 -1.75 -1.5 2.625 3.063
1 3 -1.75 -0.5 0.875 3.063
2 6 -0.75 2.5 -1.875 0.563
2 4 -0.75 0.5 -0.375 0.563
2 1 -0.75 -2.5 1.875 0.563
3 5 0.25 1.5 0.375 0.063
3 0 0.25 -3.5 -0.875 0.063
4 6 1.25 2.5 3.125 1.563
4 3 1.25 -0.5 -0.625 1.563
5 7 2.25 3.5 7.875 5.063
5 4 2.25 0.5 1.125 5.063
MX=2.75 MY=3.5 = 0 = 0 = 18.5 = 24.25
Computing the equation
¾ b = .
.
.76
¾ a = 3.5 - .76(2.75)
¾ = 1.41
¾ = 1.41 + .76X
Interpreting the coefficients
¾ Slope
z For a one unit increase in X, we predict a b
unit increase in Y
What does that mean for this study?
¾ Intercept
z The predicted value of Y when X = 0
What does that mean for this study?
Interpreting the coefficients
¾ Slope
z For each additional child, we predict
parents will do an additional .76 hours of
housework per day
¾ Intercept
z For a family with zero kids, we predict they
will do 1.41 hours of housework per day
Drawing the regression line
¾ Need to plot two points
z 𝑋, 𝑌
z Y-intercept
1
Scatterplots and
Correlation
Correlation
¾ Useful tool to assess relationships
¾ Must have two variables measured on one set of
people
¾ Correlation only measures strength of linear
association
Linear relationships are
not perfect lines
¾ Variables have variability (duh)
¾ Relationships may be generally linear
even if all points are not on the line
Magnitude of r Not all relationships are linear
2
Properties of r
¾ X & Y must be quantitative
z Interval or ratio
¾ I doe n ma e hich a iable i edic o
and which is response
z rxy = ryx
Properties of r
¾ Correlation has no units
z So r can be compared for different variables
¾ Value of r is always between -1 and +1
Computing r
¾ Consider deviations around mean of X & Y
¾ (X 𝑋) (Y 𝑌)
Cross-Product
¾ To consider X & Y together, multiply their
deviations
¾ (X 𝑋)(Y 𝑌)
¾ Sign will be positive or negative
¾ Sum of cross-pr
1. Consider the following partially completed computer printout fo.docxjackiewalcutt
1. Consider the following partially completed computer printout for a regression analysis where the dependent variable is the price of a personal computer and the independent variable is the size of the hard drive.
Based on the information provided, what is the F statistic?
About 8 .33
Just over 2.35
About 4.76
About 69.5
4 points
QUESTION 2
1. The standard error of the estimate is a measure of
total variation of the Y variable.
the variation around the sample regression line.
explained variation.
the variation of the X variable.
4 points
QUESTION 3
3.Nintendo Sony would like to test the hypothesis that a difference exists in the average age of users of a Wii, a PlayStation, or an Xbox console game. The following data represent the age of a random sample of Wii, PlayStation, and Xbox users.
Wii
PlayStation
Xbox
37
26
31
31
21
20
47
24
38
29
24
31
36
25
30
Using α = 0.05, the conclusion for this hypothesis test would be that because the test statistic is
more than the critical value, we cannot conclude that there is a difference in the average age of users of a Wii, a PlayStation, or an Xbox console game.
less than the critical value, we cannot conclude that there is a difference in the average age of users of a Wii, a PlayStation, or an Xbox console game.
more than the critical value, we can conclude that there is a difference in the average age of users of a Wii, a PlayStation, or an Xbox console game.
less than the critical value, we can conclude that there is a difference in the average age of users of a Wii, a PlayStation, or an Xbox console game.
4 points
QUESTION 4
1. The relationship of Y to four other variables was established as Y = 12 + 3X1 - 5X2 + 7X3 + 2X4. When X1 increases 5 units and X2 In a sample of n = 23, the Student's t test statistic for a correlation of r = .500 would be:
2.559
2.819
2.646
can’t say without knowing α (alpha)
4 points
QUESTION 5
1. Given the following ANOVA table (some information is missing), find the F statistic.
3.71
0.99
0.497
4.02
4 points
QUESTION 6
1. Examine the following two-factor analysis of variance table:
Complete the analysis of variance table.
MSA = 40.928, F Factor A =3.35, SSB = 85.35, Factor B df = 3, F Factor B = 2.316, MSAB = 21.859, F Factor AB = 1.8, SSE = 789.29, SSE df = 66, MSE = 12.143
MSA = 40.928, F Factor A = 3.35, SSB = 85.35, Factor B df = 4, F Factor B = 2.316, MSAB = 21.859, F Factor AB = 2.1 SSE = 789.29, SSE df = 66, MSE = 12.143
MSA = 40.698, F Factor A = 3.35, SSB = 84.35, Factor B df = 5, F Factor B = 2.316, MSAB = 21.859, F Factor AB = 2.1, SSE = 789.29, SSE df = 65, MSE = 12.143
MSA = 40.698, F Factor A = 3.35, SSB = 84.35, Factor B df = 3, F Factor B = 2.316, MSAB = 21.859, F Factor AB = 1.8, SSE = 789.29, SSE df = 65, MSE = 12.143
4 points
QUESTION 7
1. The critical value for a two-tailed test of H0: ß1 = 0 at a (alpha) = .05 in a simple regression with 22 observations is:
+ or - 1.725 ...
Question1The Tri-City School District has instituted a zero-tol.docxmakdul
Question1:
The Tri-City School District has instituted a zero-tolerance policy for students carrying any objects that could be used as weapons. The following data give the number of students suspended during each of the past 12 weeks for violating this school policy.
Find the mean, median, and mode.
Round your answers to two decimal places, where appropriate.
Mean = Median = Mode =
Question 2:
Recall the following from section 3.1 of the text. Mean : The mean for ungrouped data is obtained by dividing the sum of all values by the number of values in the data set. Median: The median is the value of the middle term in a data set that has been ranked in increasing order. If there is an even number of data, find the average of the two middle data values. Mode: The mode is the value that occurs with the highest frequency in a data set. If there are more than one data values with the highest frequency in a data set, we will have multiple modes. If all data values have the same frequency of occurrences, then the data set has no mode.
26,32,27,23,34,33,29,43,23,28
(a) Arrange the data in increasing order:
(b) Calculate the mean. The mean =
Question 3:
The following data represent the 2011 guaranteed salaries (in thousands of dollars) of the head coaches of the final eight teams in the 2011 NCAA Men's Basketball Championship. The data represent the 2011 salaries of basketball coaches of the following universities, entered in that order: Arizona, Butler, Connecticut, Florida, Kansas, Kentucky, North Carolina, and Virginia Commonwealth. (Source: www.usatoday.com)
1950,434,2300,3575,3376,3800,1655,418
Compute the range, variance and standard deviation for these data.
Round your answers to the nearest integer, where appropriate.
Range = $
Variance =
Standard deviation = $
Question 4:
The 2011 gross sales of all firms in a large city have a mean of $3.6 million and a standard deviation of $0.7 million. Using Chebyshev′s theorem, find a lower bound on the percentage of firms in this city that had 2011 gross sales between $0.8 and $6.4 million.
Round the answer to the nearest percent.
The lower bound on the percentage is at least %
Questiono 5:
The 2011 gross sales of all firms in a large city have a mean of $2.4 million and a standard deviation of $ 0.6 million. Using Chebyshev's theorem, find at least what percentage of firms in this city had 2011 gross sales of $1.0 to $3.8 million. Round your answer to the nearest whole number.
%
Question 6:
The following data give the weights (in pounds) lost by 15 members of a health club at the end of two months after joining the club.
5 10 8 7 24 12 5 13 11 10 21 9 8 11 18
(a) Calculate the approximate value of the 82nd percentile, denoted P82.
P82 =
(b) Find the percentile rank of 11.
Give the answer rounded to the nearest percent.
The percentile rank of 11 =
Question 7:
In a group of households, the national news is watched on one of the following networks – ABC, CBS ...
How to do a Chi-square test for independence in SPSS?
1. Using Chi-Square Statistic in Research
This easy tutorial will show you how to run the Chi-Square test in SPSS, and how to interpret the result.
The chi-square test of independence uses to investigate the relationship between two categorical variables that have two or more categories. In addition, the test compares the proportions, that is, the frequency of cases observed in each of the categories with values that would be expected to have if there is no relationship between the variables.
First of all, the chi-square test based on a contingency table that shows the intersection of each category of one variable with each group of the other variable.
Most of the variables show some kind of relationship. For example, there is relationship between profits and dividends paid, income and expenditure, etc. with the help of correlation analysis we can measure in one figure the degree of relationship existing between the variables.
Correlation analysis contributes to the understanding of economic behaviour, aids in locating the critically important variables on which others depend, may reveal to the economist the connection by which disturbances spread and suggest to him the paths through which stabilizing forces may become effective.
Please Subscribe to this Channel for more solutions and lectures
http://www.youtube.com/onlineteaching
Chapter 10: Correlation and Regression
10.1: Correlation
What is a disadvantage associated with the participative style of le.pdfgowravy1
What is a and b if ax+by=0 passes through the points (9,8) and (8,9)
Solution
ax+by = 0 passes through (9,8) and (8,9).
Therefore the coordinates of the points (9,8) and (8,9) should satisfy the equation ax+by = 0.
(9,8) :
a*9+b*8 = 0...........(1)
(8,9):
a*8+b*9 = 0...........(2)
Add the equations (1) and (2): 17(a+b) = 0 Or a+b = 0
Also eq(2) - eq(1) gives: a-b = 0.
So
a+b =0 and
a-b = 0.
Adding 2a = 0. Or a = 0
Subracting 2b = 0. Or b =0.
So there is no line like ax+by = 0 passes through (9,8) and (8,9).
The line passing through Two points:
The line passing through 2 points (x1,y1) and (x2,y2) is :
y-y1 = {(y2-y1)/(x2-x1)}(x-x1). Put (x1,y1) = (9,8) and (x2,y2)= (8,9).
y-8 = {(9-8)/(8-9)}(x-9)
y-8 = -1(x-9)
x+y = 1.
Therefore the line passing through (9,8) and (8,9) is :
x+y = 1 making intercepts 1 and 1 on x and y axis respectively and this line cannot be reduced to
the form ax+by = 0 which is a line through origin (making zero intercepts on x and y axis)..
What is a good one or two sentence definition for this From stan.pdfgowravy1
What is a business process? Why is adopting a process view of organizations essential to
becoming a successful manager?
Briefly describe the key business processes included in this chapter in terms of their key steps
Explain the interrelationships among the key processes included in this chapter. Why are these
interrelationships important?
Solution
A business process is a collection of linked tasks which find their end in the delivery of a service
or product to a client. A business process has also been defined as a set of activities and tasks
that, once completed, will accomplish an organizational goal.
There are three types of business processes:
A business process begins with a mission objective and ends with achievement of the business
objective. Process-oriented organizations break down the barriers of structural departments and
try to avoid functional silos.
A business process can be decomposed into several sub-processes,[citation needed] which have
their own attributes, but also contribute to achieving the goal of the super-process. The analysis
of business processes typically includes the mapping of processes and sub-processes down to
activity level.
Business Processes are designed to add value for the customer and should not include
unnecessary activities. The outcome of a well designed business process is increased
effectiveness (value for the customer) and increased efficiency (less costs for the company).
Business Processes can be modeled through a large number of methods and techniques. For
instance, the Business Process Modeling Notation is a Business Process Modelingtechnique that
can be used for drawing business processes in a workflow..
More Related Content
Similar to Tucson State University offers two MBA programs. In the first progra.pdf
1Bivariate RegressionStraight Lines¾ Simple way to.docxaulasnilda
1
Bivariate Regression
Straight Lines
¾ Simple way to describe a relationship
¾ Remember the equation for a straight line?
z y = mx + b
¾ What is m? What is b?
¾ How do you compute the equation?
(x1,y1)
(x2,y2)
What if every point is
not on the line?
¾ Straight line may be good description even
if not all points are on the line
Computing the line
when points are scattered
¾ = a + bX
¾ Y-hat means predicted value of Y
¾ Computing the slope:
¾ b = 𝑋−𝑋 𝑌−𝑌
𝑋−𝑋
¾ I ill ri e/r n, b no e al o
consider variability in X and Y
Computing the intercept
¾ a = - bX
¾ Need o pl g in al e of (X, )
¾ Can e j an Y or X!
z Line would be very different depending on
which ones you chose
¾ Must have X and Y that we know are on
the line
z mean of X and mean of Y
2
Computing the intercept
¾ Regression line will always go through the
mean of X and mean of Y
¾ A = 𝑌 - b𝑋
¾ Le r it with our example from before
X
(# of kids)
Y
(hours of
housework) 𝑋 𝑋 𝑌 𝑌 𝑋 𝑋 𝑌 𝑌 𝑋 𝑋
1 1 -1.75 -2.5 4.375 3.063
1 2 -1.75 -1.5 2.625 3.063
1 3 -1.75 -0.5 0.875 3.063
2 6 -0.75 2.5 -1.875 0.563
2 4 -0.75 0.5 -0.375 0.563
2 1 -0.75 -2.5 1.875 0.563
3 5 0.25 1.5 0.375 0.063
3 0 0.25 -3.5 -0.875 0.063
4 6 1.25 2.5 3.125 1.563
4 3 1.25 -0.5 -0.625 1.563
5 7 2.25 3.5 7.875 5.063
5 4 2.25 0.5 1.125 5.063
MX=2.75 MY=3.5 = 0 = 0 = 18.5 = 24.25
Computing the equation
¾ b = .
.
.76
¾ a = 3.5 - .76(2.75)
¾ = 1.41
¾ = 1.41 + .76X
Interpreting the coefficients
¾ Slope
z For a one unit increase in X, we predict a b
unit increase in Y
What does that mean for this study?
¾ Intercept
z The predicted value of Y when X = 0
What does that mean for this study?
Interpreting the coefficients
¾ Slope
z For each additional child, we predict
parents will do an additional .76 hours of
housework per day
¾ Intercept
z For a family with zero kids, we predict they
will do 1.41 hours of housework per day
Drawing the regression line
¾ Need to plot two points
z 𝑋, 𝑌
z Y-intercept
1
Scatterplots and
Correlation
Correlation
¾ Useful tool to assess relationships
¾ Must have two variables measured on one set of
people
¾ Correlation only measures strength of linear
association
Linear relationships are
not perfect lines
¾ Variables have variability (duh)
¾ Relationships may be generally linear
even if all points are not on the line
Magnitude of r Not all relationships are linear
2
Properties of r
¾ X & Y must be quantitative
z Interval or ratio
¾ I doe n ma e hich a iable i edic o
and which is response
z rxy = ryx
Properties of r
¾ Correlation has no units
z So r can be compared for different variables
¾ Value of r is always between -1 and +1
Computing r
¾ Consider deviations around mean of X & Y
¾ (X 𝑋) (Y 𝑌)
Cross-Product
¾ To consider X & Y together, multiply their
deviations
¾ (X 𝑋)(Y 𝑌)
¾ Sign will be positive or negative
¾ Sum of cross-pr
1. Consider the following partially completed computer printout fo.docxjackiewalcutt
1. Consider the following partially completed computer printout for a regression analysis where the dependent variable is the price of a personal computer and the independent variable is the size of the hard drive.
Based on the information provided, what is the F statistic?
About 8 .33
Just over 2.35
About 4.76
About 69.5
4 points
QUESTION 2
1. The standard error of the estimate is a measure of
total variation of the Y variable.
the variation around the sample regression line.
explained variation.
the variation of the X variable.
4 points
QUESTION 3
3.Nintendo Sony would like to test the hypothesis that a difference exists in the average age of users of a Wii, a PlayStation, or an Xbox console game. The following data represent the age of a random sample of Wii, PlayStation, and Xbox users.
Wii
PlayStation
Xbox
37
26
31
31
21
20
47
24
38
29
24
31
36
25
30
Using α = 0.05, the conclusion for this hypothesis test would be that because the test statistic is
more than the critical value, we cannot conclude that there is a difference in the average age of users of a Wii, a PlayStation, or an Xbox console game.
less than the critical value, we cannot conclude that there is a difference in the average age of users of a Wii, a PlayStation, or an Xbox console game.
more than the critical value, we can conclude that there is a difference in the average age of users of a Wii, a PlayStation, or an Xbox console game.
less than the critical value, we can conclude that there is a difference in the average age of users of a Wii, a PlayStation, or an Xbox console game.
4 points
QUESTION 4
1. The relationship of Y to four other variables was established as Y = 12 + 3X1 - 5X2 + 7X3 + 2X4. When X1 increases 5 units and X2 In a sample of n = 23, the Student's t test statistic for a correlation of r = .500 would be:
2.559
2.819
2.646
can’t say without knowing α (alpha)
4 points
QUESTION 5
1. Given the following ANOVA table (some information is missing), find the F statistic.
3.71
0.99
0.497
4.02
4 points
QUESTION 6
1. Examine the following two-factor analysis of variance table:
Complete the analysis of variance table.
MSA = 40.928, F Factor A =3.35, SSB = 85.35, Factor B df = 3, F Factor B = 2.316, MSAB = 21.859, F Factor AB = 1.8, SSE = 789.29, SSE df = 66, MSE = 12.143
MSA = 40.928, F Factor A = 3.35, SSB = 85.35, Factor B df = 4, F Factor B = 2.316, MSAB = 21.859, F Factor AB = 2.1 SSE = 789.29, SSE df = 66, MSE = 12.143
MSA = 40.698, F Factor A = 3.35, SSB = 84.35, Factor B df = 5, F Factor B = 2.316, MSAB = 21.859, F Factor AB = 2.1, SSE = 789.29, SSE df = 65, MSE = 12.143
MSA = 40.698, F Factor A = 3.35, SSB = 84.35, Factor B df = 3, F Factor B = 2.316, MSAB = 21.859, F Factor AB = 1.8, SSE = 789.29, SSE df = 65, MSE = 12.143
4 points
QUESTION 7
1. The critical value for a two-tailed test of H0: ß1 = 0 at a (alpha) = .05 in a simple regression with 22 observations is:
+ or - 1.725 ...
Question1The Tri-City School District has instituted a zero-tol.docxmakdul
Question1:
The Tri-City School District has instituted a zero-tolerance policy for students carrying any objects that could be used as weapons. The following data give the number of students suspended during each of the past 12 weeks for violating this school policy.
Find the mean, median, and mode.
Round your answers to two decimal places, where appropriate.
Mean = Median = Mode =
Question 2:
Recall the following from section 3.1 of the text. Mean : The mean for ungrouped data is obtained by dividing the sum of all values by the number of values in the data set. Median: The median is the value of the middle term in a data set that has been ranked in increasing order. If there is an even number of data, find the average of the two middle data values. Mode: The mode is the value that occurs with the highest frequency in a data set. If there are more than one data values with the highest frequency in a data set, we will have multiple modes. If all data values have the same frequency of occurrences, then the data set has no mode.
26,32,27,23,34,33,29,43,23,28
(a) Arrange the data in increasing order:
(b) Calculate the mean. The mean =
Question 3:
The following data represent the 2011 guaranteed salaries (in thousands of dollars) of the head coaches of the final eight teams in the 2011 NCAA Men's Basketball Championship. The data represent the 2011 salaries of basketball coaches of the following universities, entered in that order: Arizona, Butler, Connecticut, Florida, Kansas, Kentucky, North Carolina, and Virginia Commonwealth. (Source: www.usatoday.com)
1950,434,2300,3575,3376,3800,1655,418
Compute the range, variance and standard deviation for these data.
Round your answers to the nearest integer, where appropriate.
Range = $
Variance =
Standard deviation = $
Question 4:
The 2011 gross sales of all firms in a large city have a mean of $3.6 million and a standard deviation of $0.7 million. Using Chebyshev′s theorem, find a lower bound on the percentage of firms in this city that had 2011 gross sales between $0.8 and $6.4 million.
Round the answer to the nearest percent.
The lower bound on the percentage is at least %
Questiono 5:
The 2011 gross sales of all firms in a large city have a mean of $2.4 million and a standard deviation of $ 0.6 million. Using Chebyshev's theorem, find at least what percentage of firms in this city had 2011 gross sales of $1.0 to $3.8 million. Round your answer to the nearest whole number.
%
Question 6:
The following data give the weights (in pounds) lost by 15 members of a health club at the end of two months after joining the club.
5 10 8 7 24 12 5 13 11 10 21 9 8 11 18
(a) Calculate the approximate value of the 82nd percentile, denoted P82.
P82 =
(b) Find the percentile rank of 11.
Give the answer rounded to the nearest percent.
The percentile rank of 11 =
Question 7:
In a group of households, the national news is watched on one of the following networks – ABC, CBS ...
How to do a Chi-square test for independence in SPSS?
1. Using Chi-Square Statistic in Research
This easy tutorial will show you how to run the Chi-Square test in SPSS, and how to interpret the result.
The chi-square test of independence uses to investigate the relationship between two categorical variables that have two or more categories. In addition, the test compares the proportions, that is, the frequency of cases observed in each of the categories with values that would be expected to have if there is no relationship between the variables.
First of all, the chi-square test based on a contingency table that shows the intersection of each category of one variable with each group of the other variable.
Most of the variables show some kind of relationship. For example, there is relationship between profits and dividends paid, income and expenditure, etc. with the help of correlation analysis we can measure in one figure the degree of relationship existing between the variables.
Correlation analysis contributes to the understanding of economic behaviour, aids in locating the critically important variables on which others depend, may reveal to the economist the connection by which disturbances spread and suggest to him the paths through which stabilizing forces may become effective.
Please Subscribe to this Channel for more solutions and lectures
http://www.youtube.com/onlineteaching
Chapter 10: Correlation and Regression
10.1: Correlation
What is a disadvantage associated with the participative style of le.pdfgowravy1
What is a and b if ax+by=0 passes through the points (9,8) and (8,9)
Solution
ax+by = 0 passes through (9,8) and (8,9).
Therefore the coordinates of the points (9,8) and (8,9) should satisfy the equation ax+by = 0.
(9,8) :
a*9+b*8 = 0...........(1)
(8,9):
a*8+b*9 = 0...........(2)
Add the equations (1) and (2): 17(a+b) = 0 Or a+b = 0
Also eq(2) - eq(1) gives: a-b = 0.
So
a+b =0 and
a-b = 0.
Adding 2a = 0. Or a = 0
Subracting 2b = 0. Or b =0.
So there is no line like ax+by = 0 passes through (9,8) and (8,9).
The line passing through Two points:
The line passing through 2 points (x1,y1) and (x2,y2) is :
y-y1 = {(y2-y1)/(x2-x1)}(x-x1). Put (x1,y1) = (9,8) and (x2,y2)= (8,9).
y-8 = {(9-8)/(8-9)}(x-9)
y-8 = -1(x-9)
x+y = 1.
Therefore the line passing through (9,8) and (8,9) is :
x+y = 1 making intercepts 1 and 1 on x and y axis respectively and this line cannot be reduced to
the form ax+by = 0 which is a line through origin (making zero intercepts on x and y axis)..
What is a good one or two sentence definition for this From stan.pdfgowravy1
What is a business process? Why is adopting a process view of organizations essential to
becoming a successful manager?
Briefly describe the key business processes included in this chapter in terms of their key steps
Explain the interrelationships among the key processes included in this chapter. Why are these
interrelationships important?
Solution
A business process is a collection of linked tasks which find their end in the delivery of a service
or product to a client. A business process has also been defined as a set of activities and tasks
that, once completed, will accomplish an organizational goal.
There are three types of business processes:
A business process begins with a mission objective and ends with achievement of the business
objective. Process-oriented organizations break down the barriers of structural departments and
try to avoid functional silos.
A business process can be decomposed into several sub-processes,[citation needed] which have
their own attributes, but also contribute to achieving the goal of the super-process. The analysis
of business processes typically includes the mapping of processes and sub-processes down to
activity level.
Business Processes are designed to add value for the customer and should not include
unnecessary activities. The outcome of a well designed business process is increased
effectiveness (value for the customer) and increased efficiency (less costs for the company).
Business Processes can be modeled through a large number of methods and techniques. For
instance, the Business Process Modeling Notation is a Business Process Modelingtechnique that
can be used for drawing business processes in a workflow..
What is a data communication switch that enables many computer termi.pdfgowravy1
what is a amortization expense and when do we debit it and when do we credit it?
Solution
Amortisation expense means decline in value of goodwill, patents and other intangible
assets.Allocation to expenses of cost of intangible assets.
We debit while recognising amortisation expenses and the entry would be
Amortization expense Dr $xxx
To Accumulated amortization - Intangible Asset
We credit it
Deferred Income Dr XXX
To Deferred amortization Income XXX.
what is a currency board and how does it workSolutionTo synch.pdfgowravy1
what is 9.807m/sec2 in miles per hour per second? I have been trying this question forever and
can\'t get it. please show work so I can understand how to do it please.
Solution
9.807m/sec2 = 9.807m/(1sec*1sec)
= 9.807m/(1sec*1/3600hour) ...(since 1 second = 1/3600 hour)
=9.807*3600 m/(1sec*1hour)
= 35305.2 m per hour per second
= 35305.2*0.000621371 miles per hour per second ...(since 1 metre = 0.000621371 miles)
= 21.937 miles per hour per second.
What is a crtical review on Trends in racialethnic disparties in .pdfgowravy1
what is 7x+2/6x+3 - x-1/6x+3 substract the rational expressions
Solution
Notice that in (7x+2)/(6x+3) - (x-1)/(6x+3), the two rational expressions already have a common
denominator, 6x+3. Thus you can subtract the numerator. be careful when distributing the signs.
(7x+2)/(6x+3) - (x-1)/(6x+3)
= [(7x+2) - (x-1)]/(6x+3)
= (7x+2 - x+1)/(6x+3)
= (6x+3)/(6x+3)
=1.
What is a contingency table Provide an example.Solution .pdfgowravy1
What is 4.8 times 10 to the 8th power over 6 times 10 to the 3rd power simplified?
Solution
To start, you have:
4.8 x 10^8 / 6 x 10^3
You can cancel out 10^3 from top and bottom, which leaves you with
4.8 x 10^5 / 6
Now divide 4.8 by 6 = .8
So, you are left with .8 x 10^5
This is better expressed as 8 x 10^4..
What is a bond indenture What provisions are usually included in it.pdfgowravy1
What is 1\'s complement of (010111001)2 ?
(010111001)2
(101000111)2
(101000110)2
(001001001)2A.
(010111001)2B.
(101000111)2C.
(101000110)2D.
(001001001)2
Solution
For finding the 1\'s compliment of a number simply chage all 1s to 0s and all 0s to 1s in the
binary number
(010111001)2 => (101000110)2(option C).
what is 11 34 divided by 2SolutionWe have to find the value o.pdfgowravy1
What information does calculating standard deviation provide? How is the z-score related to
standard deviation?
Solution
Part 1:
In statistics and probability theory, standard deviation shows how much variation or
\"dispersion\" exists from the average (mean, or expected value).
A low standard deviation indicates that the data points tend to be very close to the mean; high
standard deviation indicates that the data points are spread out over a large range of values.
Part 2:
A Z-Score is a statistical measurement of a score\'s relationship to the mean in a group of scores.
A Z-score of 0 means the score is the same as the mean. A Z-score can also be positive or
negative, indicating whether it is above or below the mean and by how many standard
deviations.
The z score is how many standard deviations from the mean that your data was..
What information is provided by the sign (+ or -) of the Pearson cor.pdfgowravy1
What impact will flexible work schedules have on employees
Solution
Flexible work schedule can impact negative or possitve on a company and I will answer this with
an example.
If the schedule changes every week or month and the employe will have different shifts and
different days off then this is something an employee with a family dont really like much
because this means time away from them and it is really hard to make plans due to the fact you
dont know what your schedule could be next month, this translates into low productivity and low
efficiency. The employee might not be use to work on a night shift and he can fall sleep and an
accident happens.
On the other side, if by flexible means the employee get to choose what days and hours will
work on the next week or month then this is possitive because you can make your our agenda.
This is something that will attract talent to the organization because people want to make their
own schedule. Maybe one day he will work 15 hours and the other one only 5 , this is just an
example.
All of these scenarios will depend on the company policies..
What if we had several different type of parts and we assigned numbe.pdfgowravy1
What has contributed to the increased attention to the ethical practice of nonprofit management?
What is the unique relevance of “charity” to ethical nonprofit management?
Solution
Not for profit orgnisation are moving fast in present days. Now these organisations are also being
managed by the professionals who are apt to increase and expand the working of not for profit
organisation. Management of not for profit is quite different from the other private firms. Not for
profit management raises the fund through the donations and charities. Hence there are ample
chances of practising the fraudulent acts. In recent years, barrage of cases has surfaced involving
the management of not for profit organisation in the fraudulent practices. hence, it makes the
ample ground for imposing some ethical standards on such management..
What impact did monetary policy actions taken during the Great Reces.pdfgowravy1
What if international date line being shifted to Atlas Ocean? Most of trade partners will have
different date, States and all America continents will enter day first etc. So what can be
coincidence of this? I am asking this because I have read that samoa was shifted to have better
trade partnership with Australia.
Solution
The consequence would be confusion, if someone is further east of you it\'s natural to think
they\'re ahead of time (relative to you). Especially if you\'re used to the ubiquitous maps of the
globe (with Europe/Africa in the middle, the Americas to the left and Japan/Oceania on the
right). Confusion then might arise in some economical contexts that are highly standardised.
For example, spot transactions on the forex markets are delivered (cleared) in 2 days. If someone
behind the date line trades on your behalf you might have to wait 3 days, or just one day for the
funds to clear, depending on what side you\'re on. Also in your example, think of recurring
events (like quarterly reports, dividends, etc.), you might still be on the day before they\'re due
but time-wise (just the hours on the clock) you\'re ahead. Or if you\'re west of the date-line and
waiting for events from someone east thereof you have to wait another day.
If the explanations above are confusing then that\'s exactly the point I\'m making. So, my
opinion, if you wanted to pull off something like that without confusing people you\'d also have
to establish a new prevalent mapping of the globe, with Europe/Africa far to the \"west\" and the
Americas on the far \"east\" side. Of course, established terms, like far-east, western society, etc.
have to be recoined as well..
What form does the energy balnce take for an isolated systemSol.pdfgowravy1
What form does the energy balnce take for an isolated system?
Solution
The first law of thermodynamics is a version of the law of conservation of energy, adapted for
thermodynamic systems. The law of conservation of energy states that the total energy of an
isolated system is constant; energy can be transformed from one form to another, but cannot be
created or destroyed.
What influence does web-based information have on global citizenship.pdfgowravy1
What impact did monetary policy actions taken during the Great Recession (2007-09) have on
U.S. economic performance?
Quantitative easing and unconventional policy actions such as asset purchases and \"forward
guidance\". I think I\'m missing some things.
Solution
The consensus appears to be that the effect was large and positive. The IGM Forum asked a
panel of economists to assess the statement
\"Informed postmortems of Ben Bernanke.
what happened to the United states in the 2008 financial Crisis exp.pdfgowravy1
what happened to the United states in the 2008 financial Crisis? explain in detail
Solution
It was very touff time for US economy ,after great recession of 1930.And as per IMF it was the
worst global recession since world war 2.
According to the U.S. National Bureau of Economic Research (the official arbiter of U.S.
recessions) the U.S. recession began in December 2007 and ended in June 2009, and thus
extended over 19 months.
The crisis was caused by: Widespread failures in financial regulation, including the Federal
Reserve.
what frequently makes the difference between profitable and unprofit.pdfgowravy1
what frequently makes the difference between profitable and unprofitable online businesses
today?
Solution
profitable business firms using every piece of information and technology to generate profits and
revenues. they are using direct marketing channels, like, social media, email marketing, web
page marketing and so on to increase their revenues.
where as unprofitable firms are not able to use the available resources in a proper way to get
profits. it means they are not in a position to catch customers\' pulse and produce/promote their
products..
what features are present in New Amsterdam that identify it as a Dut.pdfgowravy1
what features are present in New Amsterdam that identify it as a Dutch colony and not as an
English colony?
Solution
I certainly agree with BZ C.\'s advice on this one. Russell Shorto\'s book is one of many
excellent books on the subject. The answer to this question tends to go into the differences
between the styles of management and the attitudes towards thier colonies of the British and the
Dutch. These things are a bit more complicated, than can really adequately be expressed here.
Hence my agreement with BZ C.
The one hint I would give is to look at how accepting the Dutch are of others not like them (the
Indians, folks from other Nationalities) and the freedoms(at least for the time) that were given to
the Dutch citizens living there as opposed to the British on the same issues. The Dutch to this
day still retain many of the same cultural qualities seen in colonial times (I had the good fortune
of living in the Netherlands for 5 1/2 months and it was quite noticeable)..
What factors should you consider in reviewing your assets What dete.pdfgowravy1
What factors should you consider in reviewing your assets? What determines the suitability of
those assets for retirement?
Solution
While reviewing assets like cash savings, investments in equity and mutual funds, properties etc.
the following factors should be considered -
(i) what is the investment goal? As per financial prudence, the farther a person is from his or her
investment goal, the higher is the quantum of risk that should be taken.
(ii) is your assets as per your risk tolerence? If you have a lower risk tolerence, your assets
should comprise mostly of bank savings, fixed deposits and immovable properties. If your risk
tolerence is high, your assets should comprise mostly of equity investments with lower exposure
to fixed deposits and other less risky assets.
In order to determine the suitability of those assets for retirement, the assets should have the
following criteria:
(a) the asset should be capable of producing a regular and recurring income. For instance one of
your assets is a residential appartment, that you are planning to give on rent. This will provide
you with regular and recurring income in the form of rental income.
(b) the assets should be liquid. Assets during retirement should be such that can be converted
into cash easily and assets with greater lock in period, that will be monitized after a long time, is
not suitable at the time of retirement..
Two common drawbacks of Pigouvian subsidy mentioned in the literatur.pdfgowravy1
Two common drawbacks of Pigouvian subsidy mentioned in the literature are related to
monetisation and measurement of social cost (Baumol) and reciprocity of social cost (Coase).
What alternatives to Pigouvian taxes are proposed in the literature? Have any of such alternative
measures been implemented in practice?
Solution
The most obvious answer is Coasian bargaining. What Coase showed in his famous \"The
Problem of Social Cost\" is that if there are no transaction costs and if utility is transferable then
it suffices to allocate property rights.
Two coins are tossed and the up faces of both coins are recorded. Li.pdfgowravy1
Two coins are tossed and the up faces of both coins are recorded. List all the simple events for
this experiment.
Solution
Even for a seemlingly trivial experiment, we must be careful when listing the simple events. At
first glance the basic outcomes seem to be Observe two heads, Observe two tails, Observe one
head and one tail. However, further reflection reveals that the last of these, Observe one head and
one tail, can be decomposedinto Head on coin 1, Tail on coin 2 and Tail on coin 1, Head on coin
2. Thus, the simple events are as follows:
1. Observe HH
2. Observe HT
3. Observe TH
4. Observe TT
(where H in the first proposition means \"Head on coin 1,\" H in the second proposition means
\"Head on coin 2,\" etc.).
Two cards are drawn from a well shuffled deck of cards. Find the pro.pdfgowravy1
Two cards are drawn from a well shuffled deck of cards. Find the probability of getting two face
cards given the first card drawn was red.
This is part d) of the other problems. They all seem so similar and I feel like I\'m stuck on the
same part with all of them.
Solution
Given that the first card drawn was red
So, probability of it being a face card , P1(f) = No. of red face cards / no. of red cards = 3/13
P2(f) = No. of remaining face cards / no. of available cards = 11/ 51
Total probability = P1 * P2 = 11/221 = 0.04977.
Unit 8 - Information and Communication Technology (Paper I).pdfThiyagu K
This slides describes the basic concepts of ICT, basics of Email, Emerging Technology and Digital Initiatives in Education. This presentations aligns with the UGC Paper I syllabus.
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
Biological screening of herbal drugs: Introduction and Need for
Phyto-Pharmacological Screening, New Strategies for evaluating
Natural Products, In vitro evaluation techniques for Antioxidants, Antimicrobial and Anticancer drugs. In vivo evaluation techniques
for Anti-inflammatory, Antiulcer, Anticancer, Wound healing, Antidiabetic, Hepatoprotective, Cardio protective, Diuretics and
Antifertility, Toxicity studies as per OECD guidelines
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
Palestine last event orientationfvgnh .pptxRaedMohamed3
An EFL lesson about the current events in Palestine. It is intended to be for intermediate students who wish to increase their listening skills through a short lesson in power point.
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
For more information, visit-www.vavaclasses.com
Overview on Edible Vaccine: Pros & Cons with Mechanism
Tucson State University offers two MBA programs. In the first progra.pdf
1. Tucson State University offers two MBA programs. In the first program, the students meet two
nights per week at the university's main campus in downtown Tucson. In the second program,
students only communicate online with the instructor. The director of the MBA experience at
Tucson wishes to compare the number of hours studied last week by the two groups of students.
A sample of 10 on-campus students and 12 online students revealed the following information.
Campus
28,
16,
42,
29,
31,
22,
50,
42,
23,
25
Online
26,
42,
65,
38,
29,
32,
59,
42,
27,
41,
46,
18
What is the Wilcoxon rank-sum test value, at the .05 significance level?(Round your answer to 2
decimal places.)
Tucson State University offers two MBA programs. In the first program, the students meet two
nights per week at the university's main campus in downtown Tucson. In the second program,
2. students only communicate online with the instructor. The director of the MBA experience at
Tucson wishes to compare the number of hours studied last week by the two groups of students.
A sample of 10 on-campus students and 12 online students revealed the following information.
Solution
Top of Form
Bottom of Form
Subchapter 12a.
The Wilcoxon Signed-Rank Test
In Subchapter 11a we examined a non-parametric alternative to the t-test for independent
samples. We now turn to consider a somewhat analogous alternative to the t-test for correlated
samples. As indicated in the main body of Chapter 12, the correlated-samples t-test makes
certain assumptions and can be meaningfully applied only insofar as these assumptions are met.
Namely,
Here again, it is not simply a question of good manners or good taste. If there is one or more of
these assumptions that we cannot reasonably suppose to be satisfied, then the t-test for correlated
samples cannot be legitimately applied.
Of all the correlated-samples situations that run afoul of these assumptions, I expect the most
common are those in which the scale of measurement for XA and XB cannot be assumed to have
the properties of an equal-interval scale. The most obvious example would be the case in which
the measures for XA and XB derive from some sort of rating scale. In any event, when the data
within two correlated samples fail to meet one or another of the assumptions of the t-test, an
appropriate non-parametric alternative can often be found in the Wilcoxon Signed-Rank Test.
To illustrate, suppose that 16 students in an introductory statistics course are presented with a
number of questions (of the sort you encountered in Chapters 5 and 6) concerning basic
probabilities. In each instance, the question takes the form "What is the probability of such-and-
such?" However, the students are not allowed to perform calculations. Their answers must be
immediate, based only on their raw intuitions. They are instructed to frame each answer in terms
of a zero to 100 percent rating scale, with 0% corresponding to P=0.0, 27% corresponding to
P=.27, and so forth. They are also told that they can give non-integer answers if they wish to
make really fine-grained distinctions; for example, 49.0635...%. (As it turns out, none do.)
The instructor of the course is particularly interested in student's responses to two of the
questions, which we will designate as question A and question B. He reasons that if students
have developed a good, solid understanding of the basic concepts, they will tend to give higher
probability ratings for question A than for question B; whereas, if they were sleeping through
3. that portion of the course, their answers will be mere shots in the dark and there will be no
overall tendency one way or the other. The instructor's hypothesis is of course directional: he
expects his students have mastered the concepts well enough to sense, if only intuitively, that the
event described in question A has the higher probability. The following table shows the
probability ratings of the 16 subjects for each of the two questions.
Subj.
XA
XB
XA—XB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
78
24
64
45
64
52
30
50
64
50
78
5. +40
mean difference = +7.75
Voilà! The observed results are consistent with the hypothesis. The probability ratings do on
average end up higher for question A than for question B. Now to determine whether the degree
of the observed difference reflects anything more than some lucky guessing.
¶Mechanics
The Wilcoxon test begins by transforming each instance of XA—XB into its absolute value,
which is accomplished simply by removing all the positive and negative signs. Thus the entries
in column 4 of the table below become those of column 5. In most applications of the Wilcoxon
procedure, the cases in which there is zero difference between XA and XB are at this point
eliminated from consideration, since they provide no useful information, and the remaining
absolute differences are then ranked from lowest to highest, with tied ranks included where
appropriate.
The guidelines for assigning tied ranks are
described in Subchapter 11a in connection
with the Mann-Whitney test.
The result of this step is shown in column 6. The entries in column 7 will then give you the clue
to why the Wilcoxon procedure is known as the signed-rank test. Here you see the same entries
as in column 6, except now we have re-attached to each rank the positive or negative sign that
was removed from the XA—XB difference in the transition from column 4 to column 5.
1
2
3
4
5
6
7
Subj.
XA
XB
original
XA—XB
absolute
9. +5
+6
+7
+8.5
+8.5
—10
+11
+12
+13
+14
W = 67.0
TN = 14
The sum of the signed ranks in column 7 is a quantity symbolized as W, which for the present
example is equal to 67. Two of the original 16 subjects were removed from consideration
because of the zero difference they produced in columns 4 and 5, so our observed value of W is
based on a sample of size N=14.
¶Logic & Procedure
Here again, as with the Mann-Whitney test, the effect of replacing the original measures with
ranks is two-fold. The first is that it brings us to focus only on the ordinal relationships among
the measures—"greater than," "less than," and "equal to"—with no illusion that these
measures have the properties of an equal-interval scale. And the second is that it transforms the
data array into a kind of closed system whose properties can then be known by dint of sheer
logic.
For openers, we know that the sum of the N unsigned ranks in column 6 will be equal to
sum
=
N(N+1)
2
From Subchapter 11a
=
14(14+1)
2
= 105
10. Thus the maximum possible positive value of W (in the case where all signs are positive) is
W=+105, and the maximum possible negative value (in the case where all signs are negative) is
W=—105. For the present example, a preponderance of positive signs among the signed ranks
would suggest that subjects tend to rate the probability higher for question A than for question B.
A preponderance of negative signs would suggest the opposite. The null hypothesis is that there
is no tendency in either direction, hence that the numbers of positive and negative signs will be
approximately equal. In that event, we would expect the value of W to approximate zero, within
the limits of random variability.
For fairly small values of N, the properties of the sampling distribution of W can be figured out
through simple (if tedious) enumeration of all the possibilities. Suppose, for example, that we
had only N=3 subjects, whose absolute (unsigned) XA—XB differences produced the untied
ranks 1, 2, and 3. The following table shows the possible combinations of plus and minus signs
that could be distributed among these ranks, along with the value of W that each combination
would produce.
Ranks
1
2
3
W
+
+
+
+6
—
+
+
+4
+
—
+
+2
+
+
—
11. 0
—
—
+
0
—
+
—
—2
+
—
—
—4
—
—
—
—6
There is a total of 8 equally probable mere-chance combinations, of which exactly one would
yield a positive value of W as large as +6, exactly two would yield a positive value as large as
+4, and so on. And similarly at the other end of the distribution: exactly one combination yields a
negative value of W as large as —6, exactly two yield negative values of W as large as —4, and
so on. Hence the probability of ending up with a positive value of W as large as +4 is 2/8=.25;
the probability of obtaining a negative value of W as large as —4 is 2/8=.25; and the "two-
tailed" probability of finding a value of ±W as large as ±4 (in either direction) is (2/8)+(2/8)=.5.
The first of the following graphs shows the sampling distribution of this N=3 situation in
pictorial form, and the other two show the corresponding distributions for the situations where
N=4 and N=5. Note that for any such situation, the number of possible combinations of plus and
minus signs is equal to 2N. Thus for N=3, 23=8; for N=4, 24=16; for N=5, 25=32, and so on.
Examine the shapes of these distributions and you will surely see where things are heading. As
the size of N increases, the sampling distribution of W comes closer and closer to the outlines of
the normal distribution. With a sample of size N=10 or greater, the approximation is close
enough to allow for the calculation of a z-ratio, which can then be referred to the unit normal
distribution. (When N is smaller than 10, the observed value of W must be referred to an exact
12. sampling distribution of the sort shown above for N=3, N=4, and N=5. A table of critical values
of W for small sample sizes will be provided toward the end of this subchapter.)
We noted earlier that on the null hypothesis we would expect the value of W to approximate
zero, within the limits of random variability. This is tantamount to saying that any particular
observed value of W belongs to a sampling distribution whose mean is equal to zero. Hence
-W = 0
Considerably less obvious is the standard deviation of the distribution. As it would be a
distraction to try to make it obvious, I will resort to another of those "it can be shown"
assertions and say simply: For any particular value of N, it can be shown that the standard
deviation of the sampling distribution of W is equal to
-W = sqrt
[
N(N+1)(2N+1)
6
]
which for the present example, with N=14, works out as
-W = sqrt
[
14(14+1)(28+1)
6
]
= ±31.86
When considering the Mann-Whitney test in Subchapter 11a we noted that the z-ratio must
include a "±.5" correction for continuity. The same is true for the Wilcoxon test, and for the
same sort of reason. The measure designated as W can assume decimal values only as an artifact
of the process of assigning tied ranks. Intrinsically, the absolute ranks—1, 2, 3, 4, etc.—on which
W is based are all integers. Thus, the structure of the z-ratio for the Wilcoxon test is
z
=
(W—W)±.5
W
The correction for continuity is "—.5" when W is greater than -W and "+.5" when W is less
than -W. Since -W is in all instances equal to zero, the simpler computational formula is
13. z
=
W—.5
W
For the present example, with N=14, W=67, and -W=±31.86, the result is
z
=
67—.5
31.86
= +2.09
From the following table of critical values of z, you can see that the observed value of z=+2.09
is significant just a shade beyond the .025 level for a directional test, which is the form of test
called for by our investigator's directional hypothesis. For a two-tailed non-directional test, it
would be significant just beyond the .05 level.
Critical Values of ±z
Level of Significance for a
Directional Test
.05
.025
.01
.005
.0005
Non-Directional Test
--
.05
.02
.01
.001
zcritical
1.645
1.960
2.326
2.576
3.291
14. When N is smaller than 10, the observed value of W must be referred to an exact sampling
distribution of the sort described earlier. The following table shows the critical values of W for
N=5 through N=9. For sample sizes smaller than N=5 there are no possible values of W that
would be significant at or beyond the baseline .05 level.
Critical Values of ±W for Small Samples:
Level of Significance for a
Directional Test
.05
.025
.01
.005
Non-Directional Test
N
--
.05
.02
.01
5
15
--
--
--
6
17
21
--
--
7
22
24
28
--
8
26