台灣地區消費者生活成本水準與價格指數替代偏誤（Substitution Bias）分析：Superlative價格指數的應用

Analyzing Taiwan's Cost of living and Substitution Bias of Consumer Price Index: An Application of Superlative Price Indexes

本文根據Superlative價格指數的衡量，發現1951－1998年間台灣地區消費者生活成本水準增加12.3倍，平均每年成長5.48％（按fixed-baseprinciple計算）。若改以拉氏消費者價格指數來衡量，則此段期間台灣地區消費者生活成本水準增加13.8倍，平均每年成長5.75％。因此改以消費者價格指數衡量生活成本水準，每年所發生的替代偏誤效果大約為0.17個百分點，與現有文獻估計結果相近。台灣在1950s與1970s年代皆處於高通膨時期，但在1970s年代以拉氏價格指數衡量消費者的生活成本水準，所產生的替代偏誤效果平均每年約為0.11％，遠低於1950s年代平均每年的0.27％，主要是因能源相關產品較不具替代彈性。本文之估計結果，除可提供政府對各項政策進行生活成本指數化公式調整的另一項重要參考依據外，同時還可用來評估現行根據拉氏消費者價格指數以調整生活成本變動時，所可能產生的所得與社會經濟福利的重分配扭曲效果。 In this paper, based on estimates of two Superlative price indexes, i.e. the Fisher Ideal and the Tornqvist price indexes, we have found that from 1951 to 1998 the general cost of living for Taiwan consumers has increased 12.3 times, equivalently to an annual average growth rate of 5.48% (in terms of fixed-base principle). Instead, if the Laspeyres Consumer price index is used as the alternative measure, then the cost of living for Taiwan consumers has increased 13.8 times over the same period, with an annual average growth rate of 5.75%. The resulting commodity substitution bias effect, i.e. overestimate of the cost of living by the consumer price index, is around 0.17 percentage points per year, which is similar to the estimates in the literature. During both 1950s and 1970s periods, Taiwan had experienced two-digit high inflation rates, however in 1970s the substitution bias effect of using consumer price index as a cost of living measure is only 0.11 percentage points per year, which is much smaller than 0.27 percentage points per year in 1950s, the reason is because that the oil-related products usually have a very low price elasticity.

In this paper, based on estimates of two Superlative price indexes, i.e. the Fisher Ideal and the Tornqvist price indexes, we have found that from 1951 to 1998 the general cost of living for Taiwan consumers has increased 12.3 times, equivalently to an annual average growth rate of 5.48% (in terms of fixed-base principle). Instead, if the Laspeyres Consumer price index is used as the alternative measure, then the cost of living for Taiwan consumers has increased 13.8 times over the same period, with an annual average growth rate of 5.75%. The resulting commodity substitution bias effect, i.e. overestimate of the cost of living by the consumer price index, is around 0.17 percentage points per year, which is similar to the estimates in the literature. During both 1950s and 1970s periods, Taiwan had experienced two-digit high inflation rates, however in 1970s the substitution bias effect of using consumer price index as a cost of living measure is only 0.11 percentage points per year, which is much smaller than 0.27 percentage points per year in 1950s, the reason is because that the oil-related products usually have a very low price elasticity.