1 / 13

Descriptive Statistics

Descriptive Statistics. What a Data Set Tells Us. Measures of Dispersion. 14.3. Compute the range of a data set. Understand how the standard deviation measures the spread of a distribution. Use the coefficient of variation to compare the standard deviations of different distributions.

gregory-vaughn
Télécharger la présentation

Descriptive Statistics

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Descriptive Statistics What a Data Set Tells Us

  2. Measures of Dispersion 14.3 • Compute the range of a data set. • Understand how the standard deviation measures the spread of a distribution. • Use the coefficient of variation to compare the standard deviations of different distributions.

  3. The Range of a Data Set

  4. The Range of a Data Set • Example: Find the range of the heights of the people listed in the accompanying table. • Solution:

  5. Standard Deviation

  6. Standard Deviation

  7. Standard Deviation

  8. Standard Deviation • Example: A company has hired six interns. After 4 months, their work records show the following number of work days missed for each worker: • 0, 2, 1, 4, 2, 3 • Find the standard deviation of this data set. • Solution: • Mean: (continued on next slide)

  9. Standard Deviation • We calculate the squares of the deviations of the data values from the mean. • Standard Deviation:

  10. Standard Deviation

  11. Standard Deviation • Example: The following are the closing prices for a stock for the past 20 trading sessions: • 37, 39, 39, 40, 40, 38, 38, 39, 40, 41, • 41, 39, 41, 42, 42, 44, 39, 40, 40, 41 • What is the standard deviation for this data set? • Solution: • Mean: (sum of the closing prices is 800) (continued on next slide)

  12. Standard Deviation • We create a table with values that will facilitate computing the standard deviation. • Standard Deviation:

  13. Standard Deviation Comparing Standard Deviations All three distributions have a mean and median of 5; however, as the spread of the distribution increases, so does the standard deviation.

More Related