CPIH uses an approach called rental equivalence to measure OOH. Rental equivalence uses the rent paid for an equivalent house as a proxy for the costs faced by an owner occupier. In other words this answers the question “how much would I have to pay in rent to live in a home like mine?” for an owner occupier. The private housing rental data underlying the OOH estimate provided in this file (covering the periods 1988-2004) is based on historical private rental data collected for the Consumer Prices Index (CPI) and Retail Prices Index (RPI). During the development of CPIH, these data were deemed not suitable for an official measure of CPIH due to the small sample size and limited number of variables available for stratification. The information in this file is provided for indicative purposes only. It does not form part of the official CPIH or OOH back series.