How can I leave blank spaces at the right end of a grouped graph (so the graph will match other graphs)?

When you make a grouped graph, there are two ways Prism can plot cells with no data (empty). Choose in the third tab of Format graph. You can choose to plot essentially a zero-height bar to represent the space that cell would have occupied, or you can ask Prism to fill in the space with no gap. 

But what if the empty cell comes at the bottom of the data table? In that case, Prism never leaves space for bottom row, regardless of how you set that option in the Format Graph dialog. Here are two ways you can make sure that Prism leaves a gap to represent that missing cell (because the cell is no longer empty):

• Enter a value for the Y value (or mean) of that spot, and then exclude that value.
• Leave Y blank, but enter a value for the SD or SEM or range. 

Now Prism will leave space on the graph for that cell, even though there is nothing to plot.