The OOHPI is a price index based on the net acquisitions approach, which measures changes in prices faced by owner-occupiers, i.e. households that live in a dwelling that they own. Both owner-occupiers' costs related to acquisition of dwellings and costs related to ownership of dwellings are covered. Country weights are numerical values assigned to each country, determining their share to the overall owner-occupied housing price, rounded to two decimal places. They are updated annually and expressed in per mille.