Table 1

Overview of the multilevel regression models

ModelAimDependent factorPotential predictors
ATo determine the difference between experimental groups regarding the within group change in patients' evaluations of care over time, taking into account clustering of data within GPsChange of patient evaluations per patient (post-intervention score minus baseline score)GP factor; group allocation (intervention v control group)
BTo determine the proportion of variation associated with systematic differences between GPs regarding post-intervention patients' evaluations of carePost-intervention patients' evaluations per patientGP factor
CTo determine the difference between experimental groups regarding post-intervention patients' evaluations of care, taking clustering of data within GPs into account (“straightforward intervention effect”)Post-intervention patients' evaluations per patientGP factor; group allocation (intervention v control group)
DTo determine the difference between experimental groups regarding post-intervention patients' evaluations of care, taking into account the clustering of data within GPs as well as the pre-intervention scores (“conditional intervention effect”)Post-intervention patients' evaluations per patientGP factor; group allocation (intervention v control group); pre-intervention score of patient evaluation (mean score per GP)
ETo determine the difference between groups defined by GP reported actions on the relevant dimensions regarding post-intervention patients' evaluations of care, taking into account the clustering of data within GPs as well as the pre-intervention scoresPost-intervention patients' evaluations per patientGP factor; group allocation defined by GP reported action on the relevant dimension (yes v no); pre-intervention score of patient evaluation