THE NON-CONSTANCY OF EQUIVALENCE SCALES

Comparisons of households of differing composition are usually achieved through the use of equivalence scales. It is well known that the choice of scales can have considerable impact on the conclusions drawn from studies of welfare and poverty. There is a considerable literature on the theoretical issues relating to equivalence scales, but applied work on income distribution and related areas almost invariably takes scales to be constant irrespective of income. This paper focuses on the relation of scale to income, by applying theoretical analysis to some simple household types. The conclusion is that scales are not constant and that current practice should be changed.     

RELATIVE INEQUALITY AND POVERTY IN GERMANY AND THE UNITED STATES USING ALTERNATIVE EQUIVALENCE SCALES

We use data from the Luxembourg Income Study to show the sensitivity of measures of relative economic well-being of persons in the U.S. and Germany using official equivalence scales and consumption-based country-specific equivalence scales developed for the two countries. Overall inequality and poverty levels are found not to be sensitive to the equivalence scale used. However, the official German equivalence scale yields quite different results from the others with respect to the relative income and poverty levels of vulnerable groups within the population, especially older single people.     

EQUIVALENCE SCALES, WELL-BEING, INEQUALITY, AND POVERTY: SENSITIVITY ESTIMATES ACROSS TEN COUNTRIES USING THE LUXEMBOURG INCOME STUDY (LIS) DATABASE

The Luxembourg Income Study (LIS) database on which this article is based offers researchers exciting new possibilities for international comparisons based on household income microdata. Among the choices the LIS microdata allows a researcher, e.g. income definition, income accounting unit, etc., is the choice of family equivalence scale, a method for estimating economic well-being by adjusting income for measurable differences in need.
The range of potential equivalence scales that can and are being used in the ten LIS countries and elsewhere to adjust incomes for size and related differences in need span a wide spectrum. The purpose of this paper is to review the available equivalence scales and to test the sensitivity of various income inequality and poverty measures to choice of equivalence scale using the LIS database. The results of our analysis indicate that choice of equivalence scale can sometimes systematically affect absolute and relative levels of poverty; and inequality and therefore rankings of countries (or population subgroups within countries). Because of these sensitivities, one must carefully consider summary statements and policy implications derived from cross-national comparisons of poverty and/or inequality.     

THE SENSITIVITY OF INCOME INEQUALITY TO CHOICE OF EQUIVALENCE SCALES

To account for the fact that a household's needs depend on its size and composition most studies on income inequality adjust the observed household incomes by equivalence scales. However, since the rationale for choosing a specific scale is rather vague the importance of testing the sensitivity of income inequality estimates to choice of equivalence scales has long been acknowledged. The sensitivity studies in the literature are restricted to equivalence scales that do not depend on the income level of the reference household which means that the effect of a rise in the household size on the scale rate does not depend on whether the household is poor or rich. By using Norwegian micro-data it is shown that the introduction of an income-dependent scale produces results that are in conflict with the widespread view of robustness of results to choice of equivalence scales.     

MEASUREMENT OF POVERTY: POLAND IN THE 1980s

This paper presents results of an examination of poverty in Poland in the 1980s. The individual welfare measure is expenditure on consumption per equivalent adult. Household equivalence scales are estimated using a quasi-exact scales trans logarithmic model. Four poverty indices are calculated. These are intended to capture the following aspects of poverty: (1) incidence, (2) relative deprivation, acid (3) social ability to eliminate poverty by income transfers. The study revealed significant changes in poverty during the investigated period, from 9 to 30 percent with persistent poverty resulting for pensioners, farmers and low educated persons.     

SEQUENTIAL STOCHASTIC DOMINANCE AND THE ROBUSTNESS OF POVERTY ORDERINGS

When comparing poverty across distributions, an analyst must select a poverty line to identify the poor, an equivalence scale to compare individuals from households of different compositions and sizes, and a poverty index to aggregate individual deprivation into an index of total poverty. A different choice of poverty line, poverty index or equivalence scale can of course reverse an initial poverty ordering. This paper develops easily-checked sequential stochastic dominance conditions that throw light on the robustness of poverty comparisons to these important measurement issues. These general conditions extend well-known results to any order of dominance, to the choice of individual versus family based aggregation, and to the estimation of "critical sets" of measurement assumptions. Our theoretical results are briefly illustrated using data for four countries drawn from the Luxembourg Income Study databases.     

HOUSEHOLD NEEDS AND POVERTY: WITH APPLICATION TO SPAIN AND THE U.K.

We examine the sensitivity of U.K.-Spanish poverty comparisons to variations in the dependence of equivalence scales on household size and composition, using evidence from national household budget surveys. We sum up these comparisons using subjective confidence levels. Taking into account the dissimilarities in the distribution of incomes and needs across countries, we find, inter alia , that although the poor are typically more numerous in Spain than in Britain, the actual headcount differences may vary by up to 10 percent of the population when needs allowances are altered, even when kept the same across the two countries. Comparisons of poverty composition across the two countries are also very sensitive to the choice of equivalence scale parameters. Generally, however, the proportion of single adults among the poor is much less important in Spain than in Britain, the reverse being true for households with three or more adults.     

Equity-regarding poverty measures: differences in needs and the role of equivalence scales

Abstract .  The paper investigates the definition of equity-regarding poverty measures when there are different household types in the population. It demonstrates the implications of a between-type regressive transfer principle for poverty measures, for the choice of poverty lines, and for the measurement of living standard. The role of equivalence scales, which are popular in empirical work on poverty measurement, is clarified.     

POVERTY IN POLAND DURING THE 1990s: ARE THE RESULTS ROBUST?

This study examines the robustness of poverty measures for Poland in the 1990s to employed methods. At least two definitions or techniques of estimation are applied to each of the following components of poverty measures: (1) household well-being; (2) poverty line; (3) equivalence scales; and (4) poverty index. Furthermore, groups at risk of poverty are selected by means of decomposition of the poverty incidence and by estimation of the probit model. Relatively robust conclusions can be reached for trends in absolute poverty incidence, which show an inverted U-shape with rapidly increasing poverty rates in 1993–1995 and declining rates since, but with continued increases in relative poverty. Some robust correlates of high poverty (low education, unemployment, rural residence, large number of children) are also found.     

THE ESTIMATION OF PENSIONER EQUIVALENCE SCALES USING SUBJECTIVE DATA

This paper uses panel data on pensioners' subjective evaluations of their financial positions to construct equivalence scales for pensioners. A pensioner couple is estimated to require an income 44 percent higher than a comparable single pensioner to reach the same standard of living. This is significantly less than the equivalence scale value implied by the ratio of state pension rates, the McClements equivalence scale value, and the scale value derived from Engel curve estimation for food expenditure using the same data source. The estimated equivalence scale value is robust to variations in the definition of the pensioner sample, the measurement of income, and the econometric model used.     

THE ESTIMATION OF PENSIONER EQUIVALENCE SCALES USING SUBJECTIVE DATA

This paper uses panel data on pensioners' subjective evaluations of their financial positions to construct equivalence scales for pensioners. A pensioner couple is estimated to require an income 44 percent higher than a comparable single pensioner to reach the same standard of living. This is significantly less than the equivalence scale value implied by the ratio of state pension rates, the McClements equivalence scale value, and the scale value derived from Engel curve estimation for food expenditure using the same data source. The estimated equivalence scale value is robust to variations in the definition of the pensioner sample, the measurement of income, and the econometric model used.     

NONCASH INCOME, EQUIVALENCE SCALES, AND THE MEASUREMENT OF ECONOMIC WELL-BEING

Little attention has been paid to the importance of consistency between the specifications of the income and the equivalence scales used in measuring economic well-being when noncash income is included in the definition of income. This article finds that inconsistency between the income and needs sides of a comparison can be important when some types of noncash income are included. An upward bias in the measured economic status of the aged when Medicare is included in income and an ordinary equivalence scale is used is presented as an example of the important effects of this consistency problem.     

A SYNTHESIS OF POVERTY LINE DEFINITIONS*

A fundamental point of discussion in poverty research is whether poverty is an absolute or a relative concept. If poverty is seen to be a situation of absolute deprivation, a poverty line will usually be defined to be independent of the general style of living in society. If poverty is considered to be a situation of relative deprivation, a poverty line will be defined in relation to the general style of living in society. The choice for one of these two approaches has important consequences for social policy, as absolute poverty may be reduced by economic growth, while relative poverty will only decrease when income inequality decreases. This paper suggests a poverty line definition that is not a priori meant to be either absolute or relative, but depends on the perception of poverty in society. If the poverty line is higher in countries with higher median income (as an indicator of “general style of living”) the poverty line is said to be relative; if the poverty line does not vary with median income, it is said to be absolute. The poverty line definition suggested appears to be a generalization of almost all well-known poverty line definitions. Poverty lines thus defined are estimated for eight European countries on the basis of a 1979 survey. The resulting lines appear to have an elasticity with respect to median income of 0.51, and hence can be said to be halfway on the scale between absolute and relative.     

A CROSS-COUNTRY STUDY OF EQUIVALENCE SCALES AND EXPENDITURE INEQUALITY ON UNIT RECORD HOUSEHOLD BUDGET DATA

Inequality comparisons require equivalence scales to account for differences in household size and composition. The multiplicity of equivalence scale models makes the sensitivity of the inequality calculations to the scale used a significant policy issue. Such an investigation based on unit records of two adult households from Italy, Australia, South Africa, Thailand, Peru, Philippines, India and Tanzania was our principal motivation. The equivalence scale varies across countries and between different types of children. Inequality rankings of countries, though not the inequality decomposition between households of different composition, are robust to the equivalence scale used.     

COMPARISON OF ALTERNATIVE TAX AND TRANSFER TREATMENT OF CHILDREN USING ADULT EQUIVALENCE SCALES

This paper estimates adult equivalence scales in the context of a nonlinear demand system using cross-section individual household data. It then evaluates the treatment of children under the tax allowance and child benefit systems on the basis of the estimated equivalence scales. The results suggest that a child benefit system allowing for economies of scale in the family is consistent with the cost of children implied by the notion of adult equivalence scale.     

EQUIVALENCE SCALES AND THE WELFARE OF CHILDREN: A COMMENT ON “IS THERE BIAS IN THE ECONOMIC LITERATURE ON EQUIVALENCE SCALES?”

In a recent issue of this journal, M. Luisa Ferriera, Reuben C. Buse, and Jan-Paul Chavas argue that the equivalence scales implicit in the official U.S. poverty line and in public welfare programs overcompensate parents for their children, with resulting negative distributional and incentive effects. We show that their analysis is based on a very particular, and ethically unappealing, assumption about the importance of children's well-being.     

CHINESE POVERTY: ASSESSING THE IMPACT OF ALTERNATIVE ASSUMPTIONS

This paper investigates how estimates of the extent and trend of consumption poverty in China between 1990 and 2004 vary as a result of alternative plausible assumptions concerning the poverty line and estimated levels of consumption. Our methodology focuses on the following sources of variation: purchasing power exchange rates (used to convert an international poverty line), alternative levels and distributions of private incomes, alternative estimates of the propensity to consume of different income groups, and alternative spatial and temporal price indices. We report national, urban and rural poverty estimates corresponding to distinct assumptions. It is widely believed that substantial poverty reduction took place in China in the 1990s, and we find this conclusion to be largely robust to the choice of assumptions, although estimates of the extent of Chinese poverty, and therefore of world poverty, in any year are greatly influenced by this choice.     

收入增长与不平等对我国贫困的影响

本文运用两组家计调查数据,采用夏普里(Shaley)分解法实证分析了20世纪90年代收入增长和收入分配的变化在我国贫困变动中的作用,并特别考虑了不同贫困线、贫困指标及等价规模对实证结果的影响。分析结果表明,90年代前半期农村减贫的成功主要归因于收入的增长和不平等的下降。在90年代后半期,农村和城市都经历了不平等的快速上升和收入的缓慢增长。因此,这段时间减贫的速度下降,甚至贫困有所增加。     

A SPECIFICATION SEPARATING FAMILY SIZE AND INDIVIDUAL AGE EFFECTS ON SUBJECTIVE EQUIVALENCE SCALES: A NOTE

This paper analyses the Kapteyn and Van Praag method of estimating equivalence scales with respect to the way family size and age composition are incorporated into the scales according to rank and age of each family member. It becomes evident that the Kapteyn/Van Praag procedure fails to distinguish between household size and individual age effects with the result that personal weights can not be used for recomposition of household types other than wife and husband families, nor can they be interpreted as showing real age dependence of personal income equivalence. For these reasons another specification of the general approach, separating both effects, is outlined. This specification distinguishes between several consumption classes within each household. Within each class, economies of scale are attached to similar individuals while differences in individual need are obtained by comparing individuals with the same rank in the different classes.     

ARE EQUIVALENCE SCALES THE SAME FOR THE UNITED STATES AND CANADA?

This research uses microdata from the 1986 Statistics Canada Family Expenditure Survey and from the 1986–88 U.S. Consumer Expenditure Survey to estimate equivalence scales using a methodology which is very similar to that employed by Statistics Canada for the estimation of Low-Income Cutoffs. Employing identical sample selection criteria and identically specified models, we find that equivalence scales for the two countries are not, in general, statistically different when estimated in the same way. The larger issue is then whether the two countries should choose the same methodology for the estimation of equivalence scales.