Problem finding interpolated values with Prism 3.

Problem:  In your step-by Step Example: Analyzing RIA and ELISA Data using Prism 3. I followed the steps in your instruction booklet. Six standard points are transformed to X=Log(X). But I didn't see "unknown sample" values calculated from the standard curve as shown in the "Interpolated X values" table. I have followed each step very carefully for three times, but I still can not get the unknown samples values from the table.There is a bug in Prism 3, but a very subtle one. In most cases, Prism will put the unpaired Y values into the transform results sheet. In some cases, it won't. If the unpaired Y values don't appear in the results sheet of the transform, then they won't be seen by the nonlinear regression program.

Fix: Go to the results sheet and click Change Parameters. Check the option to transform Y, change the option there, then uncheck. Of course you'll leave the option to transform X values checked. Most likely that will solve the problem. If not, go back to the transform parameters dialog and choose to transform Y values (as well as X) and choose the Y transform Y=Y*K. Set K=1 so this transform doesn't really do anything.

Once you can get prism to put the unpaired Y values into the transform results sheet, the nonlinear regression will work properly, including the interpolation.