1/18/2013

Descriptive Statistics (with data from Exercise 4.69 on p. 208)

• Measuring Center
  • Mean
  • Median
  • Trimmed Mean
• Measuring Spread or Variability
  • Range
  • Interquartile range
  • Variance
  • Standard Deviation
• Measuring Position
  • Percentiles
  • Five-number Summary
  • Boxplot
  • Standardized Scores
• Identifying Outliers
  • 1.5 x IQR Criterion
  • 2 or 3 standard deviations away from the mean

Standard deviation contest: You must choose 4 numbers from the set {0, 1, 2, ..., 10} with repeats allowed.

• Choose 4 numbers that have the smallest possible standard deviation.
• Choose 4 numbers that have the largest possible standard deviation.

Empirical Rule

• If the histogram of values in a data set can be reasonalby approximated by a Normal curve, then
  • approximately 68% of the observations are within 1 standard deviation of the mean
  • approximately 95% of the observations are within 2 standard deviation of the mean
  • approximately 99.7% of the observations are within 3 standard deviation of the mean

Class Exercises

The responses on the data collection cards can be found in the file p:\data\math\stats\Day1 F2013.mtw. Use this file for the first four exercises below.

1. Compare the amount of texting completed by men and women using descriptive statistics and at least two different graphical displays.
2. Compare the pulses for men and women using descriptive statistics and at least two different graphical displays.
3. Are there any outliers according to the 1.5xIQR criterion for the variable coins? amount of reading?
4. Are women better at guessing the length of the white (black) string than men? Explain.

Please complete your reading of Chapter 4 for class on Monday.