How to make two frequency distributions have the same X axis limits

Prism's frequency distribution analysis takes a stack of values and creates a frequency distribution table. You can choose the bin width, or Prism can choose it for you.

If you create a series of frequency distributions from different data tables, you'll want the range to be the same for all. However,  Prism stops making bins when it gets to the largest values. If different data sets have different ranges of data, the distributions won't be consistent and graphs of those distributions (histograms) won't align.

With Prism 5, this is easy to fix. On the Frequency Distribution dialog, choose a large value for the last bin -- large enough to include all the values in all your data sets. Choose the same value for all the analyses that you want to plot together.

With Prism 4, it is not possible to set the center of the last bin. Prism stops when it runs out of values. The only way to get consistent graphs would be to copy the results and paste onto an empty data table. Then you can add additional bins (X values), each with zero for the Y values.