Plot parameters

Another option is the Power Plot window which is opened by clicking the X-Y plot for a range of values button in the lower right corner of the main window.

By selecting the appropriate parameters for the y and the x axis, one parameter (α, power (1-β), effect size, or sample size) can be plotted as a function of another parameter. Of the remaining two parameters, one can be chosen to draw a family of graphs, while the fourth parameter is kept constant. For instance, power (1-β) can be drawn as a function of the sample size for several different population effects sizes, keeping α at a particular value.

The plot may be printed, saved, or copied by clicking the right mouse button inside the plot area.

Selecting the Table tab reveals the data underlying the plot; they may be copied to other applications.

The Power Plot window inherits all input parameters of the analysis that is active when the X-Y plot for a range of values button is pressed. Only some of these parameters can be directly manipulated in the Power Plot window. For instance, switching from a plot of a two-tailed test to that of a one-tailed test requires choosing the Tail(s): one option in the main window, followed by pressing the X-Y plot for range of values button.