Parameter transformation in sbiofitmixed

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Ben on 24 Mar 2021
Commented: Ben on 25 Mar 2021
I have a question regarding sbiofitmixed. I have fitted a model using log parameter transformation. In the NLMEresults object I can see the transformed values of the fixed effects in conjunction with their standard errors. While I can extract the original non-transformed values of the fixed effect by either using exp to transform them back or extracting them from the NLMEResults.PopulationParameterEstimates field, I can not do the same with the standard errors. I could in theory use the Delta method but I have a small sample size so that is not a proper idea here.
My question is if there is a way to extract the back-tranformed Standard Errors of the model fit using sbiofitmixed or the NLMEResults object?
Thank you for your answers in advance.

Answers (1)

Florian Augustin
Florian Augustin on 24 Mar 2021
Hi Ben,
An alternative idea would be to compute a confidence interval for the fixed effects (for example, estimatedValue + [-1.96, 1.96] * standardError). You can then back-transform the confidence interval to get a confidence interval for the population parameters. Would this give you the information you are looking for?
  1 Comment
Ben on 25 Mar 2021
It solves my problem, thank you! However I am still curious if one can obtain the back transformed values with a function, or is it not possible?

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