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Survey Data versus Administrative Data in the CPI Rent Price index, Challenges, Changes and Solutions – Case study of Iran

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Calculating the rent price index is always considered one of the most challenging topics in CPI, and there is no consensus on it. In this article, we calculated the rent price index for a two-year period using two approaches: Registry-Based Data and Survey-Based Data. The Registry-based approach uses the administrative data of the country's real estate system and the 12-Month Rolling Time Dummy Method (RTD) – a time dummy hedonic method with a rolling window – in R software. This registration data, which is regularly and monthly provided to the Statistical Center of Iran (SCI), includes all sales and rental transactions in the country, along with geographic address, age of building, area of building, type of building (apartment, villa, etc.), and the transaction price. In the survey approach, which is also the current approach of SCI, six symmetrical panels are used, from which prices are collected twice a year. Additionally, with the registration data, a more varied rent price index is obtained according to the characteristics of the dwelling, which can be useful for the policy makers of this sector.