5.7. The Normal Probability Plot
The normal probability plot helps you evaluate whether a set of data follows a normal distribution. Minitab uses an approach to the normal probability plot that transforms the vertical Y axis in a special way so that if the data are normally distributed, a plot of the data from lowest to highest will follow a straight line. JMP uses a quantile-quantile plot (known as a Q-Q plot) that transforms each value in order from lowest to highest to a Z score and then plots the data values against the Z scores. With either method, if the data are left skewed, the curve will rise more rapidly at first and then level off. If the data are right skewed, the data will rise more slowly at first and then rise at a faster rate ...
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