measures of center and spread in statistics
* Description/Instructions. The familiar measures of center (mean, median, mode) and spread (range, standard deviation, variance, and interquartile range) will generally not be directly tested on the AP exam, because you can determine these so easily on your calculator. Description/Instructions. The familiar measures of center (mean, median, mode) and spread (range, standard deviation, variance, and interquartile range) will generally not be directly tested on the AP exam, because you can determine these so easily on your calculator.