The methodology used to compile the Notaires-Insee price index for second-hand dwellings is based on hedonic models explaining the price of a dwelling according to its characteristics.

The new housing price index is based on an econometric model linking the logarithm of the price of new dwellings to different variables characterizing the property. This econometric model (also hedonic model) is estimated over two consecutive quarters. The model is said to be "adjacent periods" because it is based on the price transition between five consecutive periods.

The weights for each of the two indices correspond to the respective share of the new and the old housing in the spending by households on the acquisition of dwellings during year Y-2. These expenditures come from the housing accounts published by the Data Service and Statistical Studies (SDES) of the Ministry of ecological and solidarity Transition.

The Housing Price Index, raw as well as seasonally-adjusted, is obtained as a weighted sum of the new and existing dwelling indices.