Welfare comparisons: sequential procedures for heterogenous populations

Some analysts use sequential dominance criteria, and others use equivalence scales in combination with non-sequential dominance tests, to make welfare comparisons of joint distributions of income and needs. In this paper we present a new sequential procedure which copes with situations in which sequential dominance fails. We also demonstrate that the recommendations deriving from the sequential approach are valid for distributions of equivalent income whatever equivalence scale the analyst might adopt. Thus the paper marries together the sequential and equivalizing approaches, seen as alternatives in much previous literature. All results are specified in forms which allow for demographic differences in the populations being compared.

Horizontal Equity and Progession when Equivalence Scales are not Constant.

Household needs must be taken into account when designing an equitable income tax. If the equivalence scale is income dependent it is not transparent how to achieve equity. In this paper we explore the question of horizontal equity and the implications for progression (vertical equity), when the equivalence scale depends on income level. In particular an 'equal progression among equals' criterion is articulated and shown to be achievable along with horizontal equity under specified conditions.

The pro-poorness, growth and inequality nexus: Some findings from a simulation study

A widely accepted criterion for pro-poorness of an income growth pattern is that it should reduce a (chosen) measure of poverty by more than if all incomes were growing equiproportionately. Inequality reduction is not generally seen as either necessary or sufficient for pro-poorness. As shown in Lambert (2010), in order to conduct nuanced investigation of the pro-poorness, growth and inequality nexus, one needs at least a 3-parameter model of the income distribution. In this paper, we explore in detail the properties of inequality reduction and pro-poorness, using the Watts poverty index and Gini inequality index, when income growth takes place within each of the following models: the displaced lognormal, Singh-Maddala and Dagum distributions. We show by simulation, using empirically relevant parameter estimates, that distributional change preserving the form of each of these income distributions is, in the main, either pro-poor and inequality reducing, or pro-rich and inequality exacerbating. Instances of pro-rich and inequality reducing change do occur, but we find no evidence that distributional change could be both pro-poor and inequality exacerbating.poverty, growth, pro-poorness, income distribution.

The Gini Coefficient Reveals More

We revisit the well-known decomposition of the Gini coefficient into betweengroups, within-groups and overlap terms in the context of two groups in which the incomes in one group may be scaled and that group’s population weight modified. In this more general setting than usual, we focus on the properties of the overlap term, proving inter alia that overlap unambiguously reduces as a result of a within-group progressive transfer, and is increased by scaling up the incomes in the group with the lower mean, reaching a maximum when the two means become the same. In the case of a socially heterogeneous population and equivalized incomes, the effect on the Gini overlap of changing the income unit is determined, along with that of adjusting the equivalence scale deflator in case the income unit is the equivalent adult (such adjustment simultaneously changing the weighting of income units).

Progressivity comparisons

Analysts should correct for distributional differences before undertaking local progressivity comparisons between income tax or tax and benefit schedules. A transplant-and-compare procedure is advocated, involving 'importation' of the schedule from one regime into another, or from both into a reference scenario. The residual progression ordering over transplanted schedules then assures a global ordering of original regimes by Lorenz or Suits curves. The algorithm is advocated for use only when transplantation functions are isoelastic, and is illustrated for the Canadian, Israeli and UK tax and benefit systems.

The effect on inequality of changing one or two incomes

We examine the effect on inequality of increasing one income, and show that for two wide classes of indices a benchmark income level or position exists, dividing upper from lower incomes, such that if a lower income is raised, inequality falls, and if an upper income is raised, inequality rises. We provide a condition on the inequality orderings implicit in two inequality indices under which the one has a lower benchmark than the other for all unequal income distributions. We go on to examine the effect on the same indices of simultaneously increasing one income and decreasing another higher up the distribution, deriving results which quantify the extent of the 'bucket leak' which can be tolerated without negating the beneficial inequality effect of the transfer. Our results have implications for the inequality impacts of different income growth patterns, and of redistributive programmes (leaky or not), which are briefly discussed. Keywords: inequality index, inequality ordering, leaky bucket.

Measuring the pro-poorness of income growth within an elasticity framework

Poverty reduction has become a fundamental objective of development, and therefore a metric for assessing the effectiveness of various interventions. Economic growth can be a powerful instrument of income poverty reduction. This creates a need for meaningful ways of assessing the poverty impact of growth. This paper follows the elasticity approach to propose a measure of pro-poorness defined as a weighted average of the deviation of a growth pattern from the benchmark case. The measure can help assess pro-poorness both in terms of aggregate poverty measures, which are members of the additively separable class, and at percentiles. It also lends itself to a decomposition procedure, whereby the overall pattern of income growth can be unbundled, and the contributions of income components to overall pro-poorness identified. An application to data for Indonesia in the 1990s reveals that the amount of poverty reduction achieved over that period remains far below what would have been achieved under distributional neutrality. This conclusion is robust to the choice of a poverty measure among members of the additively separable class, and can be tracked back to changes in expenditure components.Achieving Shared Growth,Population Policies,Services&Transfers to Poor,Inequality,Rural Poverty Reduction

A Normative Approach to Measuring Classical Horizontal Inequity

This paper makes a new attack on the old problem of measuring horizontal inequity (HI). A local measure of HI is proposed, and aggregated into a global index. Whilst other approaches have captured the welfare gain which would come from eliminating HI revenue-neutrally, our global index provides a measure of the revenue gain per capita which would come from eliminating HI welfare-neutrally. When expressed as a fraction of mean post-tax income, the measure can be viewed as a negative component in the Blackorby and Donaldson (1984) index of tax progressivity, quantifying the loss of vertical performance arising from differences in the tax treatment of equals. Being money-metric, the measure can also be easily and intuitively interpreted. We propose non- parametric estimation procedures to obviate the important þidentification of equalsþ problem. To our knowledge, this provides the first consistent statistical solution to measuring classical horizontal inequity. The method is applied to the Canadian distributions of gross and net incomes in 1981 and 1990.