Содержание
- 2. Using numerical measures to describe data «Is the data in the sample centered or located around
- 3. Using numerical measures to describe data The histogram gives an idea whether the data is centered
- 4. Is the data centered around a specific value?
- 5. Numerical measures to describe data COPYRIGHT © 2013 PEARSON EDUCATION, INC. PUBLISHING AS PRENTICE HALL Ch.
- 6. Measures of the center of the data set COPYRIGHT © 2013 PEARSON EDUCATION, INC. PUBLISHING AS
- 7. The mean is the most common measure of the center of a data set For a
- 8. For a sample of n values: COPYRIGHT © 2013 PEARSON EDUCATION, INC. PUBLISHING AS PRENTICE HALL
- 9. The Mean symmetry and unimodal distribution WHEN WE HAVE A SYMMETRIC DISTRIBUTION WITH ONE MODE, THEN
- 10. Mean The most common measure for the center of a data set Affected by extreme values
- 11. Mean The most common measure for the center of a data set Affected by extreme values
- 12. Skewed distribution An outlier will distort the picture of the data. It will inflate or deflate
- 13. Median In an ordered list of data, the median is the “middle” number (50% above, 50%
- 14. Finding the Median The location of the median: If the number of values is odd (uneven),
- 15. Finding the Median The location of the median: If the number of values is even, the
- 16. Finding the median Determine the median of the following data set: 17 5 3 11 12
- 17. Finding the median Determine the median of the following data set: 17 5 3 11 12
- 18. Mode Value that occurs most often in the data set Not affected by outliers Used for
- 19. Measures of the center summary data COPYRIGHT © 2013 PEARSON EDUCATION, INC. PUBLISHING AS PRENTICE HALL
- 20. Measures of the center summary data COPYRIGHT © 2013 PEARSON EDUCATION, INC. PUBLISHING AS PRENTICE HALL
- 21. COPYRIGHT © 2013 PEARSON EDUCATION, INC. PUBLISHING AS PRENTICE HALL Ch. 2- Mean: ($3,000,000/5) = $600,000
- 22. When is which measure of the center the “best”? COPYRIGHT © 2013 PEARSON EDUCATION, INC. PUBLISHING
- 23. Shape of a Distribution Describe the shape of a distribution Describes how data is distributed The
- 24. Histogram of annual salaries (in $) for a sample of U.S. marketing managers: Describe the shape
- 25. Class exercise Eleven economists were asked to predict the percentage growth in the Consumer Price Index
- 26. Solution to class exercise Mean: 36/11 = 3.27 rounded up to 3.3 Median: 3.5 Mode: 3.7
- 27. Measures of variability The three measures of data center do not provide complete and sufficient description
- 28. Measures of Variability DR SUSANNE HANSEN SARAL Same center, different variation Variation Variance Standard Deviation Coefficient
- 29. Quartiles DR SUSANNE HANSEN SARAL
- 30. Quartiles DR SUSANNE HANSEN SARAL 25% 25% 25% 25% Q1 Q2 Q3
- 31. How to calculate quartiles manually DR SUSANNE HANSEN SARAL Find a quartile by determining the value
- 32. Quartiles DR SUSANNE HANSEN SARAL (n = 9 1st Quartile = the value located in the
- 33. Quartiles DR SUSANNE HANSEN SARAL Sample Ranked Data: 11 12 14 16 16 17 18 21
- 34. Quartiles and Enron case
- 35. Range Simplest measure of variation Difference between the largest and the smallest observations: COPYRIGHT © 2013
- 36. Range – Example Enron case Range = Maximum value – minimum value Enron data range =
- 37. Disadvantages of the Range Ignores the way in which data is distributed DR SUSANNE HANSEN SARAL
- 38. Disadvantages of the Range Sensitive to outliers DR SUSANNE HANSEN SARAL 1,1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,3,3,3,3,4,5 1,1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,3,3,3,3,4,120 Range = 5
- 39. Range: short-comings as a good measure for variability Because the range does not provide us with
- 40. Interquartile Range COPYRIGHT © 2013 PEARSON EDUCATION, INC. PUBLISHING AS PRENTICE HALL Ch. 2- 25 %
- 41. Interquartile Range The interquartile range (IQR) measures the spread of the data in the middle 50%
- 42. Interquartile Range Raw data: 6 8 10 12 14 9 11 7 13 11 n =
- 44. Скачать презентацию