Actually, the regression coefficients are correct. You are not able to see it because of the default factor coding that JMP uses when analyzing a designed experiment.

You see this prediction expression:

Notice that we should not expect the slope parameter to be 3.14 because that is not what is multiplying X^2. Instead, the 706.5 is multiplying ((x1-25)/15)*((x1-25)/15)).

If you save that prediction formula from the red triangle and open up that formula from the data table, you will see this:

Now from the red triangle at the top (highlighted here), choose Simplify:

You will see the modified equation with the 3.14 that you expected.

The 3925-157*X1 appears because the model that I simplified only had the quadratic term in it. That leads to these "extra terms" that should not be part of what we know as the true model.

Now if we had fit the model following hierarchy (as recommended) and simplified this equation:

we will get exactly what you want (subject to round-off error)!

Dan Obermiller