2.3 Measures of Dispersion
-Which Airplane Would You Use?
Two measures of dispersion:
Def: Standard Deviation: the average distance from the mean.
Def: z-score: indicates how many standard deviations above or below the mean your score lies.
Empirical Rule: 68% of scores are within 1 standard deviation from the mean
95% of scores are within 2 standard deviations from the mean, and
99% of scores are within 3 standard deviations from the mean
Formula for computing z-score by hand: