Donor imputation is used where the number of residential property transactions is extremely low in the quarter and a suitable ‘donor’ series is available for imputation. This approach imputes a price movement from a donor series such as another stratum, dwelling type or city. For example, imputing a movement in the Hobart attached dwellings price index from the movement in the Hobart house price index.

Mean imputation is used where the number of residential property transactions in a stratum is extremely low in the quarter and a suitable donor series is not available for imputation. This approach derives the stratum movement using the average (mean) price movement of all other strata for that dwelling type in that city. For example, imputing a price movement for a particular stratum in the Brisbane house price index using the average price movement of all other strata in the house price index for Brisbane.

Further information about imputation in the residential property price indexes can be found in the linked Methodology page below under How the data is processed.

For the June 2020 quarter, donor imputation was used for Hobart and Darwin due to substantial falls in residential property transactions. The movement in each city's house price index was used to impute the movement in its attached dwellings price index for the June 2020 quarter.

The table below summarises the imputation methods applied to the indexes particularly affected by COVID-19 impacts in the June quarter 2020.