Graphs of Block Data - Normal Probability Plot: Block Columns

When you select a block of data within a spreadsheet and select Graphs of Block Data - Normal Prob. Plot: Block Columns  from the Graphs menu (or right-click on the selected block of data and select Graphs of Block Data - Normal Prob. Plot: Block Columns  from the resulting shortcut menu) a normal probability plot is created for the values in each column of the block, and is then plotted in separate graph windows.

To create one graph (a multiple normal probability plot) to allow for comparisons between the normality of the distribution of values in the block columns,

1. select Graphs of Block Data - Custom Graph from Block by Column from the Graphs menu,

2. click the More button on the Select Graph dialog,

3. and select the Single Window (Overlaid) option button.

To create a normal probability plot for each of the rows in the block, select Graphs of Block Data - Custom Graph from Block by Row from the Graphs menu.

Note that you can also create probability plots for entire variables (columns) or cases (rows) by selecting Graphs of Block Data - Custom Graph for Entire Column or Graphs of Block Data - Custom Graph for Entire Row. Use the custom graph options to create a variety of probability plots (e.g., detrended, half-normal, and normal).

Note that if the data in columns (or rows) that are compared in the graph have different ranges, then the comparison will be biased, as the range will affect the slope of the fit. To avoid this bias, bring the data to a common range (e.g., via standardization or other transformations) before creating this graph.

For more information on normal probability plots, see Graphs of Input Data - Probability Plot by... or Stats Graphs - Probability Plots.