Property prices index numbers and derived indices

Purpose – A useful instrument to understand and examine the inner workings of the property trade is devising index numbers of property prices based on historical sequences of market prices. The present work aims at the definition of index numbers of property prices, proposing an innovative methodology compared with what usually recurs in literature. The purpose of this paper is to discuss these issues. Design/methodology/approach – The analysis proposed, based on the mechanisms of formation of stock indices, investigates the analogies between stock and property information, according to the peculiarities of the property trade, leading to a methodology approach, derived from Simple Price Index Method, able to consider possible anomalies in the collected sample of purchase prices, using weighting coefficients based on reliability coefficients of sale prices of properties. Findings – The novel approach proposed has led to the definition of a original methodology useful to appraise property price index numbers and other derived indicators, effective for interpreting and identifying real estate market dynamics in a given area of study, regarded as a standard estimating methodology applicable to any geographical context and kind of property. Practical implications – Methodology proposed in this work is useful to revalue real estate sales price and to consider presence of anomalous sales price in property samples. Originality/value – The calculation of index numbers of prices is usually based on Simple Price Index Methods. Literature shows large use of different methods, such as Repeat Sales Method, Hedonic Price Method, Repeat Value Model. The present work propose an innovative methodology able to detect the presence of possible anomalous market prices in the representative sample, using an appropriate vector of weights in order to take into account the level of reliability of market data.