The Laspeyres bias in the Spanish consumer price index

The CPI compares the cost of acquiring a reference quantity vector at current and base prices. Such reference vector is the vector of mean quantities actually bought by a reference population, whose consumption patterns are investigated during a period τ prior to the index base period 0. This paper shows that unless the price change between these two dates is taken into account, the CPI ceases to be a proper statistical price index of the Laspeyres type. Among several negative consequences, the most important is that this omission produces a bias in the measurement of inflation: the ‘Laspeyres bias’. Using Spanish data, the size of the Laspeyres bias is estimated at -0.061% per year, during 1992–1998. The Laspeyres bias in shorter time periods reached -0.122% per year in 1992, and -0.108 in 1997.     

Calculating the Candy Price Index: A Classroom Inflation Experiment

In this classroom experiment, students develop a price index based on candy-purchasing decisions made by members of their class. They use their index to practice calculating inflation rates and to consider the strengths and weaknesses of the consumer price index (CPI). Instructors can use the experiment as an introduction to the topic of inflation and how it is measured. The exercise also provides a concrete example of the sources of bias in the CPI, promoting discussion of the measures the Bureau of Labor Statistics has taken to reduce bias. The experiment, including follow-up discussion, fits into a 50-minute class period. The authors and other professors have used the exercise in introductory and intermediate macroeconomics courses, in classes of 10 to 135 students.     

消费者价格指数能反映生活成本吗 基于城镇各收入阶层食品生活成本估计

本文基于超级指数和可变偏好效用函数方法构建了1997-2011年中国城镇各收入阶层家庭食品消费生活成本指数,并在此基础上将各阶层生活成本指数与其消费者价格指数进行对比,检验消费者价格指数对生活成本的反映能力。样本期间内消费者价格指数与生活成本指数比较接近,可以较好地反映生活成本的变化。基于超级指数方法的结果显示,样本期间内替代偏差与家庭收入负相关,与通货膨胀正相关,而由于偏好改变所造成的偏差在绝对值水平上则与收入水平正相关。     

Do disaggregated CPI data improve the accuracy of inflation forecasts?

In this paper, we evaluate the role of using consumer price index (CPI) disaggregated data to improve the accuracy of inflation forecasts. Our forecasting approach is based on extracting the factors from the subcomponents of the CPI at the highest degree of disaggregation. The data set contains 54 macroeconomic series and 243 CPI subcomponents from 1992 to 2009 for Mexico. We find that the factor models that include disaggregated data outperform the benchmark autoregressive model and the factor models containing alternative groups of macroeconomic variables. We provide evidence that using disaggregated price data improves forecasting performance. The forecasts of the factor models that extract the information from the CPI disaggregated data are as accurate as the forecasts from the survey of experts.     

Estimating the true cost of living for households with different incomes using data from Taiwan

This empirical study investigates why the true costs of living for different income groups in Taiwan as measured by the superlative Törnqvist price index have grown dissimilarly over the sample period. Specifically, it shows that using the aggregate Cost of Living (COL) estimates for the entire households as is commonly practiced would produce noticeable group bias effect in measurement. Also the magnitude of the commodity substitution bias in the conventional Consumer Price Index (CPI) is found to be positively related to household income in general. Because of the presence of these two biases, the true COL for households belonging to the two ends of the income spectrum is found to be over-estimated. This article is therefore in full agreement with Arrow's proposition that an alternative and separate set of price index be constructed.     

我国商品期货价格指数与宏观经济指标关系的实证研究简

通过考察我国商品期货价格指数与主要宏观经济变量之间的相互影响关系,发现商品期货价格指数对物价、国内生产总值、利率、人民币汇率均有明显的引导作用和直接影响,并且能够领先CPI指标约5-7个月。商品期货价格指数作为CPI的先行指标具有一定的可行性。     

A HEDONIC PRICE INDEX FOR AIRLINE TRAVEL

Our research takes an exhaustive approach to measurement issues in price index construction for the BLS airfare index. We pursue a number of the objectives for dealing with the biases that the 1997 CPI Commission recommended and detail a protocol for data collection and analysis that can be replicated and can be enhanced by availability of additional data sources. We find an upward bias in the BLS airfare index over the period considered. However, because of issues of practicality and implementability of the methods we utilize in our analysis, the goals of the Commission recommendations remain illusive and problematic in being more broadly applied to other components of the CPI.     

消费者价格指数与生产者价格指数:谁带动谁?

消费者价格指数(CPI)与生产者价格指数(PPI)是相互联系并有显著区别的概念。两者之间的因果关系或非因果关系有多种可能情形。本文对中国消费者价格指数(CPI)和生产者价格指数(PPI)2001年1月至2008年7月数据的格兰杰因果检验结果显示,在所考察时期内,消费者价格指数是生产者价格指数变动的格兰杰原因,后者经过1—3个月左右的时滞对前者的变动作出反应。这个结果很可能意味着,在所考察时期内,在影响以消费者价格指数(CPI)来衡量的国内通货膨胀中,需求方面的因素相对大于供给方面的作用,尽管需求因素和供给因素都共同地影响了国内通货膨胀的走势。     

Causality between consumer price and producer price: Evidence from Mexico

We examine the relationship between two inflation indices, consumer price index (CPI) and producer price index (PPI) for Mexico, a case study country which has successfully implemented inflation targeting after the economic crisis and high inflationary situation in 1995. Since the causality running from PPI to CPI exemplifies the cost push nature of inflation and the opposite is the indicator of demand pull inflation, this analysis could provide significant policy implications. We contribute to the literature by decomposing the time–frequency relationship between CPI and PPI through continuous wavelet approach. Our results indicate a bidirectional relationship between CPI and PPI. In short periods (1 to 7 months scale) CPI is leading PPI, while for longer periods (8 to 32 months scale) PPI is the leading variable.     

Is there a quality bias in the Canadian CPI? Evidence from microdata

Rising consumer prices may reflect shifts by consumers to new higher‐priced products, mostly for durable and semi‐durable goods. I apply Bils’ (2009) methodology to newly available Canadian consumer price data for non‐shelter goods and services to estimate how price increases can be divided between quality growth and price inflation. I find that less than one third of observed price increases during model changeovers should be attributed to quality growth. This implies overall price inflation close to inflation measured by the official index. I conclude that, according to Bils’ methodology, the quality bias is not an important source of potential mismeasurement of CPI inflation in Canada.     

我国粮食价格与CPI关系研究

本文利用1998年1月-2010年10月的月度CPI数据和粮食批发价格指数对粮食价格和CPI的关系进行了定性和定量分析。实证结果表明,两者之间存在长期和短期关系,从长期来看,粮食价格每上涨1%会使CPI上涨0.336%;从短期来看,粮价对CPI有滞后1期的影响,CPI对粮价有滞后3期的影响。综合考虑影响粮食价格的国际效应、供给效应、市场预期效应和政策效应,未来几个月我国粮价将有所上涨,但涨幅不会很大。     

Quality-corrected price indices: the case of the Dutch new passenger car market, 1990–1999

Market dynamics and technological developments constitute a major challenge to the proper measurement of the price evolution of durable goods. In this study, hedonic methods are used to estimate quality-corrected price indices of new passenger cars in the Netherlands, 1990–1999. Use is made of a huge set of price, quantity and quality information about 11,000 car models, obtained from different sources. During the observation period the nominal price level of all available car models increased about 20% on average, while the shares of car models with airbags, tinted glass and power steering increased from almost nothing to about 90%. Matched model price indices and the official CPI for new passenger cars, which partially account for quality-adjustments, estimate the price increase to be equal to 10.6–14.2% respectively 11.2% for the 1990–1999 period. By contrast, the hedonic Fisher-like price indices based on the preferred annually estimated brand-weighted semi-log hedonic model, lead to price changes varying from +?2.3% to ??3.4% (depending on the choice of weight variable, and the use of fixed or varying reference periods in the index construction) and thereby fall 8.9 to 14.6 percentage points below the official figures, over the period 1990–1999. The pooled adjacent-years model holds an intermediate position with a predicted quality-corrected price decrease of 1.8% over the observation period, which is 13.0 points below the CPI.     

Scenarios for a redistribution of unpaid work in the Netherlands

The consumer price index (CPI) is used in the United States to measure changes in the cost of living. Since the CPI is used to index the official U.S. poverty guidelines and to establish eligibility criteria for various public assistance programs, a change in the methodology used to calculate the CPI would impact the accuracy of poverty statistics and, more importantly, poor families' access to public assistance. Since the majority of these poor families are headed by women, the CPI becomes a critical issue for feminist economics. In December 1996 the United States Senate Finance Committee's Advisory Commission to Study the Consumer Price Index issued its final report which concluded that use of the consumer price index results in widespread substantial overindexing. This paper uses the basic needs budgets (BNB) to evaluate changes in the cost of living for low-income families. The author compares the cost of the BNBs for single-parent families in 1983 and 1996 and finds that the cost of the bundle of goods and services included in the BNBs has increased faster than the CPI. The author finds similar results for two-parent families.     

CPI Quality Adjustment and Productivity Growth: Railway Services in Japan

In recent years quality adjustment of price indices has been vigorously explored and the hedonic regression method has become popular in official statistics. In service sectors, however, the current CPI seems not to have been successfully adjusted to accommodate quality changes. In this paper I focus on the railway industry in Japan, where quality change is a vital factor in the measurement of price indices and productivity. Using hedonic regressions to adjust CPI railway fares, the paper suggests that there may be a significant degree of upward bias in the current CPI railway fares. Also, this leads to the results that the total factor productivity (TFP) of the Japanese railway industry, which is calculated by using the newly adjusted CPI as a deflator, has been improved contrary to previous research on this issue.     

Cost-of-living indexes and demographic change

The Consumer Price Index (CPI), although not without problems, is the most often used mechanism for adjusting contracts for cost-of-living changes in the US. The US Bureau of Labor Statistics lists several problems associated with using the CPI as a cost-of-living index where the proportion of 2-worker families is increasing, population is shifting, and work week hours are changing. This study shows how to compute cost-of-living indexes which are inexpensive to update, use less restrictive assumptions about consumer preferences, do not require statistical estimation, and handle the problem of increasing numbers of families where both the husband and wife work. This study attempts to how widely in fact the CPI varies with alternative true cost-of-living varies with alternative true cost-of-living indexes although in the end this de facto cost-of-living measure holds up quite well. In times of severe price inflation people change their preferences by substitution, necessitating a flexible cost-of-living index that accounts for this fundamental economic behavior.     

消费物价指数与生产者价格指数:谁带动谁?

The consumer price index (CPI) and producer price index (PPI) are interrelated but significantly different concepts. Relationships between the two indices may be that of causality or non-causality. The paper conducts a Granger-causality test on China’s CPI and PPI data for the period from January 2001 to August 2008, and finds that CPI Granger causes the change in PPI, and the latter reacts to the former with a time lag of 1–3 months. The result may suggest that in contemporary Chinese economy, demand-side factors have played a more important role than supply-side factors, although the two sides both have influences on domestic inflation trend which is measured by CPI. __________ Translated from Jingji Yanjiu 经济研究 (Economic Research Journal), 2008, (11): 16–26     

需求拉动,还是投资推动——基于新一轮通胀周期的实证研究

对通货膨胀及其成因的研究一直是宏观经济学与政府政策的一项重要内容。本文通过建立向量误差修正模型(VECM),对我国1997～2009年新一周期的通货膨胀进行实证研究。结果发现,月度消费价格指数(CPI)和工业品出厂价格指数(PPI)之间存在长期均衡关系,其格兰杰因果关系走向是CPI影响PPI,即价格传导走向是自下而上,而不是相反。这也就是说,总需求的扩张仍是此阶段通货膨胀的根源,所谓结构性通胀、输入型通胀等非典型通胀的解释得不到实证支持。研究还发现,在解释现阶段通胀中,供给价格弹性和巨型经济体是需要注意的两个因素。     

资源税的价格效应分析

2011年11月1日实施的资源税改革将原油和天然气由原来的从量计征改为从价计征,税率均为销售额的5％-10％,其他的资源税税日依旧是从量计征。这次的资源税改革使社会上普遍关注资源税税改后导致的资源性产品价格上涨．进而对居民消费价格指数CPI产生很大压力。文章采用实证分析方法分析资源税是否会严重影响CPI,研究结果表明资源税对CPI影响不大。     

Demand system estimation in the absence of price data: an application of Stone-Lewbel price indices

This article evaluates the feasibility of estimating a system of demand equations in the absence of price information using the approach developed by Lewbel (1989). Stone-Lewbel (SL) price indices for commodity groups are constructed using information on the budget shares and the Consumer Price Indices (CPIs) of the goods comprising the commodity groups, which allows for household-level prices to be recovered. This study evaluates how susceptible are elasticities and marginal effects estimates from traditional parametric demand systems to the CPI used in the construction of the SL prices. To do this, three alternative regional CPIs are considered for the construction of the SL prices: monthly, quarterly and a constant (unity) price index. Elasticities and marginal effect estimates are computed for eight food commodity groups using the Exact Affine Stone Index (EASI) model as the parametric demand system and data from the United States Consumer Expenditure Survey. The estimates proved to be robust to the alternative regional CPIs considered in the construction of SL price indices, even to the absence of one. Hence, the results suggest that it is possible to accurately estimate a demand system even in the absence of price information.     

Using food prices and consumption to examine Chinese cost of living

This paper considers two approaches to examining potential bias in China's consumer price index: (i) inferring true changes in cost of living from consumer behaviour; and (ii) creating alternative price indices to compare with official indices. For (i), our semi‐parametric estimates agree with the recent finding of a large understatement in increases to the true cost of living. For (ii), we focus on food prices and explore potential causes of bias. We find some evidence of a new‐good bias. China's large‐scale migration also causes changes in the cost of living that are not reflected in the consumer price index.