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Methodological question: adjusting for confounders in logistic regression

Cross Validated Asked by tohweizhong on December 20, 2021

I have three attributes in a dataset (D0), representing the binary response of success or failure (R), some form of treatment or treatment group (T), and a potential confounder (C) respectively. Building a logistic regression model (with eg. logit link) to predict R with T and C as covariates, I can get the log-odds of success for R, whilst adjusting for C.

My question is: does it make sense to generate an “adjusted dataset” D1, whereby R has been adjusted for C? To be more specific, T and C in D1 will be exactly the same as that of in D0, but the values of R in D1 will be different: R in D1 will be dictated by the coefficients in the logistic model.

I recognize that for simple OLS regression, this is trivial. But since logistic regression is predicting log-odds (and hence also predicting the probabilities Pr(R = success)), there is an additional step to convert the probabilities into actual binary values.

Typically, we can use a data-driven threshold to convert the probabilities into binary values, by looking at various metrics such as specificity, sensitivity, etc. But these are driven by predictions and accuracy – what I am looking at is statistical adjustments.

Any ideas? Is such a procedure of generating “adjusted datasets” with logistic regression even valid?

Thanks!

One Answer

What (I think) you are talking about is essentially a multi-way contingency table. The standard way to model this sort of thing is to consider a categorical variable X which takes the value D0 in dataset 0 and D1 in dataset 1.

The rest of your discussion essentially focuses around conditional odds ratios so the short answer is yes. Look up section 5.4.1 in 'Categorical Data Analysis' by Agresti ( I am sure all other books on categorical data analysis have a section on this but this is the one I use)

Answered by Sid on December 20, 2021

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