WEBVTT 1 00:00:04.000 --> 00:00:11.500 Researchers need to know not only the typical score, but also the spread of scores 2 00:00:11.500 --> 00:00:18.000 Are the scores tightly clustered around the mean or are they widely scattered? 3 00:00:18.000 --> 00:00:23.600 We call this the variability of the distribution. 4 00:00:23.600 --> 00:00:31.000 Two common measures of variability are the range and the standard deviation.