1. Compare the following heights in inches: BoysGirls 7261 7464 7065 6866 6968 7067 6865 6963 6762 7065 7166 67 64 66

2. Computational Formulas and IQR’s

3. Computational Formula: This is an easier computational formula that contains no rounding.

4. Let’s try it! 7 18 22 34 42

5. You try one! 4 8 12 18 22 34 38

6. Is the standard deviation affected by outliers? 5 7 5 8 9 5 7 5 8 29

7. The standard deviation is sensitive to extreme values.

8. 67 65 68 70 74 60 61 64 67 68 The following data represents the heights of some students in my class. a.Find the mean & st. dev. b.What % are within 1 st. dev. Of the mean? c.What % are within 2 st. dev. Of the mean?

9. IQR – Interquartile Range This is the measure of variability that is not affected by outliers. It’s based on quartiles.

10. 25% - This is the median of the lower ½ of the sample. - This is the median. - This is the median of the upper ½ of the sample.

11. 18242527 29303334

12. Find IQR 1213161822242740

13. Find IQR 8101114162022262832

14. Find IQR 456671022

15. If normal distribution – then you can estimate the standard deviation with the IQR. Standard Deviation *Can also be use to check to see if a distribution is normal – if much larger then it’s skewed.

16. Homework Worksheet Use the new formula to compute the standard deviation.

17. Now for the Lab!