Term	Historical Imputation
Synonym
Related Term
Source of Definition
Short Definition
Statistical Activity	Survey design

Definition
Historical imputation is when a previous value of a non-respondent is used for the imputation of a current value. This value may be bought forward unchanged (un-weighted historical imputation), or have some kind of movement applied to it (weighted historical imputation).

Example
1. A business does not respond to a question that asks for the number of full and part time employees. However, they responded to this question last period, so this previous value is imputed as the current value. This is un-weighted historical imputation.

2. A business does not give the value of quarterly turnover in March. They did respond last quarter though (in December), so the previous value is used, multiplied by the forward movement factor for similar units. This is weighted historical imputation.