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# Week 3 lecture_math_221_nov_2012

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Week 3 Statistics (Math 221) Slides

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### Week 3 lecture_math_221_nov_2012

1. 1. 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. 2.  Data Collection  Understand and distinguish between  Sampling  Census  Experiments  Simulations  Etc.
3. 3.  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. 4.  Knowthe difference between Qualitative and Quantitative Data
5. 5.  Types of Sampling  Random  Stratified  Cluster  Systematic  Convenience
6. 6.  Populations and Samples  Parameters and Statistics
7. 7.  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.  For example if you are given the standard deviation is “3” and asked what the variance is, you would note it as “9” because 3^2 is 9.  If you were given the variance as 4.7 and asked for the standard deviation, you would note it as “2.17” because √4.7 = 2.17
8. 8.  Be able to get a regression equation. Example  Data (4, 30), (4,35), (5,36), (6,42), (8,48)
9. 9.  Be able to get a regression equation. Example  Data (4, 30), (4,35), (5,36), (6,42), (8,48)
10. 10.  Be able to get a regression equation. Example  Data (4, 30), (4,35), (5,36), (6,42), (8,48)
11. 11.  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. 12.  Use a multiple regression equation. • “Plug and Chug” (Plug in the values and chug out the answer) • Example y = -6.5 +12a + 5.1b where “a” is a vocabulary score and “b” is a skills test score. y predicts the person’s score on a job performance test. Predict a job test score for a person who made a 50 as a vocabulary score and got a 7 as a skills test . y = -6.5 +12(50) + 5.1 (7) y = 629.2
13. 13.  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 almost none, I would probably note it is as “NO CORRELATION” • + would be positive correlation, - would be negative correlation • For example, -0.58 would be moderate negative correlation
14. 14. From Page 487 in our text
15. 15.  Be able to create a stem and leaf plot  Use Minitab! Determine descriptive statistics. • Mean, Median, Mode, Range, Variance, Standard Deviation  Use Minitab!
16. 16.  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
17. 17.  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)
18. 18.  Midpoint of second class is 11.5 Number of Fish Frequency 0-7 98+15 = 23divided by 2 8-15 15gives you 11.5 16-23 12 24-31 3
19. 19.  What are the class boundaries of the third class?15.5 and 23.5 Number of Fish Frequency 0-7 9 8-15 15 Subtract .5 from 16-23 12 the lower to get 24-31 3 15.5 and add .5 to the upper to get 23.5
20. 20.  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 39Total your Frequency column, the total is your denominator for your fractional relative frequencies. You could also have noted these in decimal form.
21. 21.  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 often post helpful things there for fun and you can look at old posts that may be helpful.