This document provides a review for a week 3 quiz in a math 221 class. It covers topics like data collection, descriptive and inferential statistics, qualitative and quantitative data, different sampling methods, populations and samples, standard deviation and variance, regression equations, correlation coefficients, and how to create and interpret stem-and-leaf plots. Examples are provided for regression equations, using a multiple regression equation, and calculating relative frequencies from a stem-and-leaf plot. Students are encouraged to use online resources provided by the instructor on Facebook to further review these topics.

1. Week 3 Quiz Review for
Math 221
B. Heard
(These may not be copied, reproduced, or
posted in an online classroom without my
permission. Students may download one copy
for personal use.)

2. Week 3 Quiz Review
• Data Collection
– Sampling
– Census
– Experiments
– Simulations
– Etc.

3. Week 3 Quiz Review
• Descriptive & Inferential Statistics
– Know the difference
– Descriptive - This is a set of methods to describe
data that we have collected.
– Inferential - This is a set of methods used to make
a generalization, estimate, prediction or decision.

4. Week 3 Quiz Review
• Know the difference between Qualitative and
Quantitative Data

5. Week 3 Quiz Review
• Types of Sampling
– Random
– Stratified
– Cluster
– Systematic
– Convenience

6. Week 3 Quiz Review
• Populations and Samples
– Parameters and Statistics

7. Week 3 Quiz Review
• Standard Deviation and Variance
– How to calculate and mathematical relationship.
– Variance is the Standard Deviation squared.
– Standard Deviation is the square root of the
Variance.

8. Week 3 Quiz Review
• Be able to get a regression equation.
• Example
– Data (4, 30), (4,35), (5,36), (6,42), (8,48)

9. Week 3 Quiz Review
• Be able to get a regression equation.
• Example
– Data (4, 30), (4,35), (5,36), (6,42), (8,48)

10. Week 3 Quiz Review
• Be able to get a regression equation.
• Example
– Data (4, 30), (4,35), (5,36), (6,42), (8,48)

11. Week 3 Quiz Review
• Be able to get a regression equation.
• Example
– Data (4, 30), (4,35), (5,36), (6,42), (8,48)
This would be written
as y = 3.982x + 16.70

12. Week 3 Quiz Review
• Use a multiple regression equation.
• Plug and Chug
• y = -6.5 +12a + 5.1 b where a is test score and b is
a competency score. y predicts the person’s score
on a job test.
• Predict a job test score for a person who made a
50 on the test and got a 7 as a competency score.
• y = -6.5 +12(50) + 5.1 (7)
• Y = 629.2

13. Week 3 Quiz Review
• Correlation Coefficients, also noted as “r”
• Range from -1 to +1
• .75 to 1 is strong
• .5 to .75 is moderate
• .25 to .5 is weak
• 0 to .25 is very weak (closer to zero, almost none)
• + would be positive correlation, - would be negative
correlation
• For example, -0.58 would be moderate negative
correlation

14. Week 3 Quiz Review
• Be able to create a stem and leaf plot and
determine descriptive statistics.
• Mean
• Median
• Mode
• Range
• Variance
• Standard Deviation
• Use Minitab!

15. Week 3 Quiz Review
• Identify Class Width
• Identify Midpoint of certain classes
• Identify class boundaries
• Give the relative frequency
• Fishing Tournament Data below is an example
Number of Fish Frequency
0-7 9
8-15 15
16-23 12
24-31 3

16. Week 3 Quiz Review
• Class Width is 8
Number of Fish Frequency
0-7 9
8-15 15
16-23 12
24-31 3
8-0 = 8, or you could have
said 15 – 7 = 8, or count
on your fingers,
0,1,2,3,4,5,6,7
(There are eight numbers,
don’t let it fool you)

17. Week 3 Quiz Review
• Midpoint of second class is 11.5
Number of Fish Frequency
0-7 9
8-15 15
16-23 12
24-31 3
8+15 = 23
divided by 2
gives you 11.5

18. Week 3 Quiz Review
• What are the class boundaries of the third
class? 15.5 and 23.5
Number of Fish Frequency
0-7 9
8-15 15
16-23 12
24-31 3
Subtract .5 from
the lower to get
15.5 and add .5 to
the upper to get
23.5

19. Week 3 Quiz Review
• Give the relative frequency of all classes
Number of Fish Frequency Relative Frequency
0-7 9 9/39
8-15 15 15/39
16-23 12 12/39
24-31 3 3/39
Total of 39

20. Week 3 Quiz Review
• Come see me at the “Statcave”
• www.facebook.com/statcave
• You DO NOT have to be a Facebook person to see
these.
• If you are, become a fan.
• IT IS NOT REQUIRED TO BE ON FACEBOOK. IT’S
SOMETHING I DO FOR FUN.
• I post charts there because it is easy for me to do.