I aim to assess the effects of difficulty (continuous variable) and trial type (0/1) on whether a subject has been correct in a logistic regression model. However, I have also measured subjects impulsivity scores, which is a continuous variable. For impulsivity I only have one estimate per subject, for the other variables I have trial type dependent estimates.
So far I have estimated a logistic regression model per subject, normalized all coefficients by the vector norm of the weight vector per subject and correlated the regression coefficients with the impulsivity scores on a group level. I wondered whether this is a reasonable approach? I could also estimate a single mixed effect model and incorporate subject as a random factor. However, there is again no way to incorporate the continuous variable impulsivity in that model, right? How would you proceed with that problem?