## What method does Intellectus Statistics use to impute missing values?

Intellectus Statistics uses two methods of imputation, both described in the book *Data Analysis Using Regression and Multilevel/Hierarchical Models* by Andrew Gelman and Jennifer Hill. For Nominal and Ordinal variables, the missing values are imputed by randomly sampling from the observed categories. For Scale variables, a type of regression imputation is used. First, the missing values are imputed using the predicted values from the regression (the mean in this case). Last, a random amount is added to each imputed value based on the prediction error.