Central tendency

• What do descriptive statistics include?

  Measures of central tendency
• What do measures of central tendency provide information about?

  The most typical values in a data set
• What are the three measures of central tendency?

  • Mean
  • Median
  • Mode
• How is the mean calculated?

  Add all scores and divide by total scores
• What is the mean of the data set: 5, 7, 7, 9, 10, 11, 12, 14, 15, 17?

  10.7
• Why is the mean considered the most sensitive measure of central tendency?

  It includes all scores in the calculation
• How can extreme values affect the mean?

  They can distort the mean significantly
• What happens to the mean if 17 is replaced with 98 in the data set?

  The mean becomes 18.8
• What is the median?

  The middle value in a data set
• How is the median determined in an even number of scores?

  It is halfway between the two middle scores
• What is the median of the data set: 5, 7, 7, 9, 10, 11, 12, 14, 15, 17?

  10.5
• Why is the median less sensitive than the mean?

  It ignores the actual values of extreme scores
• What is the mode?

  The most frequently occurring score in a data set
• What does it mean if a data set is bi-modal?

  It has two modes
• Why is the mode considered a crude measure?

  It may not represent the whole data set
• What is the mode of the data set: 5, 7, 7, 9, 10, 11, 12, 14, 15, 17?


  7
• When is the mode the only useful measure?

  When data is in categories
• How would you identify the most typical dessert from a class survey?

  Select the modal group