Numerical Measures of Central Tendency and Variability

Read these sections and complete the questions at the end of each section. First, we will define central tendency and introduce mean, median, and mode. We will then elaborate on median and mean and discusses their strengths and weaknesses in measuring central tendency. Finally, we'll address variability, range, interquartile range, variance, and the standard deviation. 

Median and Mean


  1. This is a definition of the median.

  2. This is a definition of the mean

  3. This is a definition of the mean.

  4. The mean and the median are only the same when a distribution is symmetric. The mean and median are different when the distribution is skewed.
  5. 15: The median minimizes the absolute deviations. To find the median, order the numbers from smallest to largest, and then find the middle number.

  6. The mean minimizes the squared deviations. To find the mean, find the sum of the values (140) and divide by number of values in your data set (5). 140/5 = 28

  7. The mean (in this case, 6.5) is the point at which a distribution balances.