Inquiry 1 written and oral reports are due in lab the week of 9/29.

1. Inquiry 1 written and oral reports are due in lab the week of 9/29. Today: More Statisticsoutliers and R2

2. Outliers… 2, 2, 2, 2, 2, 3, 3, 3, 4, 4, 5, 5, 5, 6, 7, 121, 130 Median = 4 Mean = 18

3. Is there a numerical way to determine the accuracy of our analysis? 2, 2, 2, 2, 2, 3, 3, 3, 4, 4, 5, 5, 5, 6, 7, 121, 130 Mean = 18 Standard deviation = 40.5 Standard deviation is a measure of variability.

4. Outliers: When is data invalid?

5. Outliers: When is data invalid? Not simply when you want it to be.

6. Outliers: When is data invalid? Not simply when you want it to be. Dixon’s Q test can determine if a value is statistically an outlier.

7. |(suspect value – nearest value)| Q = |(largest value – smallest value)| Dixon’s Q test can determine if a value is statistically an outlier.

8. |(suspect value – nearest value)| Q = |(largest value – smallest value)| Dixon’s Q test can determine if a value is statistically an outlier. Example: results from a blood test…789, 700, 772, 766, 777

9. |(suspect value – nearest value)| Q = |(largest value – smallest value)| Dixon’s Q test can determine if a value is statistically an outlier. Example: results from a blood test…789, 700, 772, 766, 777

10. |(suspect value – nearest value)| Q = |(largest value – smallest value)| Dixon’s Q test can determine if a value is statistically an outlier. Example: results from a blood test…789, 700, 772, 766, 777 Q=|(700 – 766)| ÷ |(789 – 700)|

11. |(suspect value – nearest value)| Q = |(largest value – smallest value)| Dixon’s Q test can determine if a value is statistically an outlier. Example: results from a blood test…789, 700, 772, 766, 777 Q =|(700 – 766)| ÷ |(789 – 700)| = 0.742

12. |(suspect value – nearest value)| Q = |(largest value – smallest value)| Dixon’s Q test can determine if a value is statistically an outlier. Example: results from a blood test…789, 700, 772, 766, 777 Q =|(700 – 766)| ÷ |(789 – 700)| = 0.742 So?

13. You need the critical values for Q table: If Q calc > Q critrejected From: E.P. King, J. Am. Statist. Assoc. 48: 531 (1958)

14. You need the critical values for Q table: If Q calc > Q critthan the outlier can be rejected Q calc = 0.742 Q crit = 0.717 = rejection From: E.P. King, J. Am. Statist. Assoc. 48: 531 (1958)

15. What can outliers tell us?

16. If you made a mistake, you should have already accounted for that.

17. Outliers can lead to important and fascinating discoveries. Transposons “jumping genes” were discovered because they did not fit known modes of inheritance.

18. What about relating 2 variables?

19. Is there a numerical way to determine the accuracy of our analysis? 2, 2, 2, 2, 2, 3, 3, 3, 4, 4, 5, 5, 5, 6, 7, 121, 130 Mean = 18 Standard deviation = 40.5 Standard deviation is a measure of variability.

20. What about relating 2 variables? R2 gives a measure of fit to a line. If R2 = 1 the data fits perfectly to a straight line If R2 = 0 there is no correlation between the data

21. R2 gives a measure of fit to a line. birth month vs birth day

22. birth month vs birth day Birth day birth month

23. Protein quantity vs absorbance

24. We will practice T-test, outliers, and R2 in lab. Also, you will have time to begin forming groups for Inquiry 2.

25. Inquiry 1 written and oral reports are due in lab the week of 9/29. Today: More Statisticsoutliers and R2