topic Re: inverse prediction using quadratic model in Discussions

inverse prediction using quadratic model

billi — Tue, 30 Jul 2019 17:27:21 GMT

I calculated predicted x from linear fit using fit model > inverse prediction. Is it possible to do the same using the quadratic model.

Re: inverse prediction using quadratic model

Mark_Bailey — Tue, 30 Jul 2019 18:03:31 GMT

Generally, no.

What is the inverse prediction for Y = 10?

Re: inverse prediction using quadratic model

billi — Wed, 14 Aug 2019 19:02:28 GMT

@Mark_Bailey I am trying to calculate 'x' from 'y' using quadratic standard curves so I can compare with 'x' calculated using same standard data fir to a linear model using jmp. I know I can do this graphically by using crosshairs tool with overlaid linear and quadratic functions. Is there any other way to calculate 'x' from the quadratic response function using JMP to show the difference between this and corresponding values calculated using the linear model?

Re: inverse prediction using quadratic model

Mark_Bailey — Thu, 15 Aug 2019 11:35:43 GMT

I believe you are using the Bivariate platform. Use the Fit Least Squares platform instead. The Inverse Prediction command in this platform still does not work with quadratic models but there is another option. Follow these steps:

Select Analyze > Fit Model.
Select response column and click Y.
Select factor column.
Click Macros and select Polynomial to Degree.
Change Emphasis to Minimal Report.
Click Run.
Click the red triangle at the top and select Factor Profiling > Profiler.
Click the red triangle next to Prediction Profiler and select Optimization and Desirability > Desirability Functions.
Control-click on the Desirability plot at the right end of the top row of plots.
Change the goal to Match Target. Do NOT change the desirability values otherwise.
Enter the target response value as the Middle value.
Enter Low and High values that surround the target. These values are not critical.
Click OK.
Click the red triangle next to Prediction Profiler and select Optimization and Desirability > Maximize Desirability.

The inverse prediction appears as the red number below the profiler for the factor.

Re: inverse prediction using quadratic model

billi — Fri, 16 Aug 2019 18:22:58 GMT

@Mark_Bailey Thank you for your response. It worked and I got results for the inverse prediction for linear model but I'll not be able to get inverse prediction for quadratic model in JMP. Correct?

Re: inverse prediction using quadratic model

Mark_Bailey — Fri, 16 Aug 2019 19:23:42 GMT

Is what correct?

I followed the steps above using the Big Class data table. The weight is in the Y role and I added height and height^2 terms to the model. I defined the desirability function to match a target of Y = 120. Here is the result:

The inverse prediction is 66.3 inches.

Re: inverse prediction using quadratic model

friedrich — Tue, 23 Feb 2021 11:18:32 GMT

Hello,

I've just discovered this topic as I faced the same problem. The solution works to have the inverse prediction but it is without the confidence interval. In my case I am comparing two models : quadratic and logistic and I would like to compare the inverse predictions from both. With the logistic there is the inverse prediction module which gives the confidence interval. I miss the same for the quadratic model. Does anyone knows if this feature will be added to quadratic models?