Up to Wave R (except for Wave O), HGROOM was collected only in the first interview with new households. In case a household had moved or (from Wave H onwards) whether a household‘s housing unit size changed due to renovations or additions (up to Wave G, these households filled out a “green” questionnaire). In Wave O, the information had been asked again in order to correct for mistakes that may have occurred in carrying forward or in the process of imputation. From Wave S onwards, the question on the number of rooms has been asked to all households annually.

For old households still residing at their old address and neither having moved nor renovated their dwelling, the information on the number of rooms is carried forward as a status variable in order to provide valid current information. Analogously, the information is carried back to fill gaps if a households missed to state the number of rooms in the first year(s) they moved to a new housing.

In case, the information on the number of rooms is still missing, it is imputed simultaneously with other variables using Stata‘s chained imputation procedure. Imputed values are not carried forward. For information on the imputation procedure, see the description of HGRENT.