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How does JMP do BoxCox transformations?

DWS

I have recently been converting JMP formulas into Excel using the python code option. I have been unable to actually transfer any formula (MLR) involving a BoxCox transformation. It have manually done the calculations following the formula and have gone numbers in the multimillions instead of 100 thousands where it should be. If someone knows if the formula is already converted back or If I need to and what I need to do to apply the inverse BoxCox to get it back in normal terms. I don't know if I am missing something or if the Python Code through the publish formula option is missing something. I was hoping that someone could explain how JMP preforms the Box Cox transformation so that I can better understand it to potentially fix it. I tried to attach the code of the formula but it wouldn't allow me to post. Any help would be appreciated.

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Mark_Zwald

Documentation and formula for Box-Cox transformation is available here: https://www.jmp.com/support/help/en/18.2/index.shtml#page/jmp/boxcox-y-transformation.shtml

MRB3855

Hi @DWS : This may be helpful as well.

https://community.jmp.com/t5/Discussions/How-to-understand-Lambda1-and-Lambda2-for-Box-Cox-transformation/m-p/614578#M81444

DWS

Thank this did help me better understand BoxCox transformations in general but not how JMP does them necessarily. The following question I believe would help me understand. The numbers that JMP shows in the Parameter Estimates section, for a BoxCox formula, are those just BoxCox transformed or have they already been inverse transformed back into understandable units?

MRB3855

@DWS If all you do is select "Box Cox Transformation" under the "Factor Profiling" menu, then no transformation is applied and the parameter estimates are based on Y. But if you further Refit with the box-cox transformation (red triangle in the "Box Cox Transformations" output), the parameter estimates are based on the transformed Y.

DWS

OK, just to be clear, the formula that is give after I have clicked "Refit with Transformation", in that new menu , that formula and that parameter estimates are not transformed then inverse transformed back into real units but are left in transformed units. If this is the case then is is possible to know the formula JMP uses to inverse transform them because, it does give inverse normal units in the save column prediction formula? or should I apply a normal inverse transformation? Also, do you know this from experience? or is this written somewhere because I could not find it anywhere. Sorry for the number of questions.