Fig. 2From: Multiple imputation methods for handling missing values in a longitudinal categorical variable with restrictions on transitions over time: a simulation studya) Scenarios to be imputed under stage 1 of the restriction process (never-smoker); b) Scenarios to be imputed under stage 2 of the restriction process (ex- or current-smoker); c) Scenarios to be imputed under stage 3 of the restriction process (never-, ex- or current-smoker); Grey boxes refer to data to be imputed at each stage if incompleteBack to article page