Graphs of Input
Data - Probability Plot Graphs of Input
Data - Probability PlotThese Graphs of Input Data plots visualize normality of the distribution of the currently highlighted variable. The assumption of normality (that the data follow a normal distribution) often needs to be tested, since many statistical procedures assume that the distribution of an analyzed variable is normal. You can choose from three different types of normal probability plots to visually verify the normality of a variable when you select this option.
Note that you can visually compare the normality of the values of a
variable in graphs identified by a grouping variable by selecting Probability Plot By ... from the Graphs - Graphs of Input Data submenu.
Many other types of probability plots are
available in STATISTICA's Graphs
menu graphs. In order to produce normal probability plots of the values
in cases (and not variables), use either the Graphs
of Block Data - Custom Graph for Entire Row or Graphs
of Block Data - Custom Graph from Block by Row option from the spreadsheet
shortcut menu (instead of transposing your data file). Note that if more
than one row (or column) is highlighted, then a multiple normal probability
plot will be produced. For a general overview of the graphics facilities
in STATISTICA, see Graphs
in STATISTICA.
