Measures of Central Tendency and Variation

A measure of central tendency is a value that represents a typical, or central, entry of a data set. The three most commonly used measures of central tendency are the mean, median and mode. A way to measure the variation (or spread) of a data set is to find the range, variance and standard deviation.

Annual Salaries: Sample annual salaries (in the thousands of dollars) for accountants in Dallas are listed.

41.6 50.0 49.5 38.7 39.9 44.7 44.7 47.8 40.5

1. Using the annual salaries data set, find the mean, median, and mode.

mean: ________

median: _______

mode: _________

2. Interpret the meaning of each measure of central tendency (mean, median, mode) with respect to annual salaries?

3. Using the annual salaries data set, find the range, variance and standard deviation.

range: __________

variance: _____________

standard deviation: __________

4. Interpret the meaning of each measure of variation (range, variance, standard deviation) with respect to annual salaries?

5. If the sample annual salary for Dallas is changed by adding the data point 72.3

Compute the mean: ______

6. Based on the change, what valid conclusion can be drawn between means?

7. How does this additional data point affect the median? Please provide an explanation to support your inference.