The POWERMUTT Project: Standard Scores and the Normal ...

If variables are normally distributed, standard scores become extremely useful. It turns out that, in a normal distribution, 68 percent of cases will be within one standard deviation of the mean (that is, will have a z score within the range of ±1), 95 percent will be within two standard deviations of the mean, and 99.7 percent will be within ... ................
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