Törnqvist Formula for Сalculating a Consumer Price Index in Russia: Theory and Practice

Abstract

The article reflects the author’s position on the adjustment of the so-called substitution bias, which affects the value of the consumer price index, currently calculated using the Laspeyres formula. The author proposes a solution to the problem of the adequacy of statistical measurements of the dynamics of consumer prices in the case when, as a result of changing cost of the consumer basket, a buyer replaces a relatively expensive product with a relatively cheaper one. This solution is based on the existing index construction methodology (axiomatic, economic and stochastic approaches). The article substantiates the use of the Törnqvist formula, which has better properties in comparison with other formulae used in the construction of superlative indices. The authors calculated the Törnqvist price index for Russia based on Rosstat methodology and data using country-level quarterly group price indices and shares of consumer spending. To evaluate the results of empirical testing Laspeyres price index was compiled using the same quarterly data as the Törnqvist index. The values of the Törnqvist price index in most cases are less than the price dynamics obtained according to the Laspeyres formula. This conclusion is proved both theoretically and empirically, and it is confirmed for Russia as well. However, due to the non-observance of the conditions of smooth trends in consumer prices, the difference between the values of the Törnqvist and Laspeyres indices is significantly larger in certain quarters than that presented in empirical studies in other countries. Consumer price index, calculated using the Törnqvist formula, in the system of indicators of price statistics in Russia can be defined as an indicator that specifies the main consumer price index. Calculation of its value is necessary for a more realistic description of the processes taking place in the consumer market.