Bug: Stacked bars graphs don't work unless bars begin at Y=0

In all versions of Prism up to 5.04 and 5.0d, stacked bar graphs only work properly when the bars begin at Y=0. There is really no reason to use a different baseline. The whole point of bar graphs is to compare the heights of bars as a way to compare the Y values. If the baseline is not 0, then you can't conclude when one bar is twice as high as another that the value for the first group is twice that of the second. When the bar baseline is not zero, some slices in the stacked bar graph may be missing entirely. 

If you really, really want the bars to begin at a baseline other than zero, here is a workaround.  First transform the data so that the baseline is zero, and plot that graph. If you want the baseline to begin at 100, then subtract 100 from all the values. Then use the Additional ticks portion at the bottom of the Format Axis dialog, to tell Prism (for example), to write "100" at Y=0.0, and "200" at Y=100...