Statistical methods
REGRESSION
Classical linear logistic regression models were run, with a binary outcome variable equal to 1 if an eligible child was vaccinated, and 0 otherwise. The models included previous vaccination and demographic variables (age and sex) as fixed effects, in addition to the intervention. It also included GP practice as a random effect, to account for variation not explained by the fixed effects. Analyses were carried out using R, version 4.0.0.