as with averages, researchers need to transform data into a form conducive to interpretation, comparisons, and statistical analysis measures of dispersion summarize differences in the data, how the numbers differ from one another. Measures of Dispersion

Three Common Measures of Dispersion range range variance variance standard deviation standard deviation

range the simplest measure of dispersion the simplest measure of dispersion represents the distance between the highest and lowest scores represents the distance between the highest and lowest scores sensitive to extreme scores sensitive to extreme scores insensitive to differences between scores within a distribution insensitive to differences between scores within a distribution Golf Scores range = 34

variance indicates the amount of variation or variability in a distribution indicates the amount of variation or variability in a distribution defined as “the average of the sum of the squared deviations” defined as “the average of the sum of the squared deviations” “good” variance (between group) versus “bad” variance (within group) “good” variance (between group) versus “bad” variance (within group)

standard deviation the most sensitive measure of dispersion the most sensitive measure of dispersion the standard deviation reflects the average amount of dispersion in a distribution the standard deviation reflects the average amount of dispersion in a distribution defined as the square root of the variance defined as the square root of the variance standard deviations and significance tests standard deviations and significance tests

standard deviations under the normal distribution