In a normal probability plot, the data in the selected column of the Table are plotted against a normal distribution in such a way that the points should form approximately a straight line. Departures from a straight line indicate departures from normality.

Settings

Number of quantiles

the number of quantile points, n, in the plot. From this number n, the quantile points are determined as follows: the last quantile point is q_n = 0.5^1/n and the first quantile point is q₁=1–q_n. The intermediate quantile points q_i are determined according to q_i=(i – 0.3175)/(n + 0.365), where i runs from 2 to n–1.

Number of sigmas

determines the horizontal and vertical drawing ranges in units of standard deviations.