Improved Mean Methods of Imputation

Replacing missing values of a variable with the mean of the non-missing values is a simple and natural way to impute values fortunately in the case where data is missing completely at random. Following a short review of this method we consider thus possible improvements, are called the shrinkage method, a second called the weighted interval method, and a third called the known variance method. Estimates of the population mean obtained from each of these methods are compared to the mean method both analytically and by means of numerical examples.