Logit transform in Fit Model with custom bounds

Phil_Kay

Hi,

 

A customer has asked for something. I think it is one for the Wish List. But I just want confirmation that it is not already possible.

 

They would like to be able to use the transform columns capability in Fit Model to provide a Logit transformation of responses. But instead of having the bounds 0 to 1, they would like to use their own bounds.

 

The logit transform does this:

"Calculates the inverse of the logistic function for the selected column (where p is in the range of 0 to 1): logit(p) = log (p/1-p)"

 

The customer can create their own transform column but A) this takes a long time with multiple responses and the fit model results are not back-transformed in the report.

 

The customer previously used Design Expert, which has the capability to fit with custom logit transforms (I can confirm this from using DE myself). They dont want to have to switch back to DE for this capability.

 

Thanks,
Phil

Chris_Kirchberg

Hey Phil,

 

I am not sure how to do this within Fit Model for custom transformations, but one can apply a formula to many columns at the same time.  I use Standardize Attributes from the Cols Menu to do this. I select all the new blank columns ive created to contain a formula referencing the response that I need to transform, then got to Standardize Attributess, then select Statndarize Properties>Formula. I check Substitute Column Reference then click on Edit Formula to make my transformed column.

This expedites creating the transformed responses, but it does back transform in the report.

I think a request into development for a custom transform in Fit Model to be available would be nice.