Prism 7 Windows bug: Grand means or medians won't plot if the data are formatted for entry of any kind of error value.

Prism 7 added the opportunity when plotting grouped superimposed scatter graphs to plot the grand mean or grand median. This works fine if you entered data on the Grouped table as single Y values, or as side-by-side replicates. But if you formatted the table for entry of Mean, N and SD or SEM (or any error values), Prism 7 Windows won't plot the grand mean or median. The only workaround is to change the format of the data table (or switch to Prism Mac).  This bug is all releases of Prism 7 for Windows.