I am working on longitudinal data (from a panel survey) that were analyzed using mixed effects modelling to estimate risk differences, the outcome is contact with any health provider, and predictors being both fixed (like socio demographic factors) and random (like having symptoms). I am finding it difficult to interprete the results of the adjusted models, certainly because I don't fully understand the concept of this modelling technique. Could you advise on any reference for (non statistician) clinicians? Thank you