Measuring the impact of price changes on poverty

This paper develops a methodology to measure the impact of price changes on poverty measured by an entire class of additive separable poverty measures. This impact is captured by means of the price elasticity of poverty. The total effect of changes in price on poverty is explained in terms of two components, income and distribution effects. The income effect measures the change in poverty when all prices increase uniformly, whereas the distribution effect captures the change in poverty because of changes in relative prices. Using this decomposition, the paper derives an empirically operational index, which reveals whether the price changes have been pro-poor or anti-poor. The paper also derives a new price index for the poor. While this index can be computed for any poverty measures, our empirical analysis applied to Brazil is based on three poverty measures, the head-count ratio, the poverty gap ratio and the severity of poverty. The empirical analysis shows that price changes in Brazil during the 1999–2006 periods have been anti-poor. Nevertheless, during the last 2 to 3 years, the price changes have affected the poor less adversely than the non-poor.     

Economic Growth and Poverty Reduction by Region: Chile 1990‐96

This article examines the evolution of poverty in Chile during 1990‐96, a period of rapid economic growth. It shows that Chile has embarked on a significant poverty‐reduction trajectory. The robustness of this result is examined by using nonparametric estimates of the income distribution and a stochastic dominance test. Growth is an important factor in explaining the poverty reduction that has occurred. Using the Datt‐Ravallion decomposition, it accounts for over 85% of poverty reduction at the national level. However, the pattern varies significantly across regions. Both growth, and its contribution to poverty reduction, vary significantly among regions. This seems to reflect the sectoral composition of growth across regions, with export‐oriented activities producing a larger poverty‐reduction impact.     

Poverty, income distribution and CGE micro-simulation modeling: Does the functional form of distribution matter?

This paper explores income distribution modeling approaches for poverty analysis in a CGE micro-simulation context. Income distribution functional forms such as the lognormal, Pareto, beta distribution and empirical methods are currently used in CGE models in parallel with the estimation of FGT poverty indices. The particular methods or functional forms used in this context are not always clearly defined and justified. In this paper, we investigate and provide better criteria for selecting a functional distribution for poverty analysis. To achieve this, we apply parametric estimation to seven functional forms and compare the results to a purely “empirical” method. The results showed that no single form is more appropriate in all instances or for all household subgroups. The choice of a modeling approach should be motivated by a search for best fit and should be based on appropriate statistical tests. Selecting inappropriate distributional forms can lead to biased results in terms of poverty analysis. Introducing functional forms in the empirical approach can also provide greater confidence in the results obtained.

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An erratum to this article can be found at     

A general class of inequality elasticities of poverty

Many authors have recently emphasized the crucial role of income inequalities in the design of efficient policies aimed at reducing poverty. However, the link between variations in the degree of inequality and variations in poverty is not well documented. The literature, for instance, does not provide any satisfying tool for predicting how a small relative variation in the Gini index may be associated with a variation in the headcount index. In the present paper, we define a family of Lorenz curve transformations that can directly be interpreted in terms of relative variations of known inequality measures. Then, we extend Kakwani’s (Rev Income Wealth 39(2):121–139, 1993) methodology for the calculation of inequality elasticities of poverty. Improvements are threefold with respect to Kakwani’s work. First, our formulas are not confined to the sole Gini index. Secondly, they embrace the uncertainty and the complexity of the mechanical link between inequality and poverty. Third, using some flexible functional form, one can easily perform an accurate estimation of the point inequality elasticities of poverty corresponding to observed variations of a given income distribution. We also propose a simple measure that may be helpful to assess how “pro-poor” are inequality variations by comparing the observed elasticities with the set of theoretical elasticities that could be obtained from the initial income distribution.     

Tracing out the effects of demographic changes on the income distribution

During the 1980s and 1990s fertility decisions varied significantly and not uniformly along the income distribution in Argentina. In this paper we study the effects of these demographic changes on income poverty and inequality by applying microeconometric decomposition techniques. In particular, we simulate the equivalized household income distribution that would emerge if individuals observed in a given base year had taken fertility decisions as they did in another different year. The results suggest that these demographic factors have contributed considerably to the changes in poverty and inequality experienced by Argentina since the 1980s.     

Flat rate taxes and relative poverty measurement

We provide a systematic analysis of the impact of revenue-neutral changes to the parameters of a flat rate tax system on the level of relative poverty (where the poverty line is some fraction of either the mean or the median post-tax income level). We also perform a similar analysis for a negative income tax system. We find that the choice of poverty line type has important consequences in respect of how changes to the tax parameters affect the level of relative poverty. Our results are illustrated with a numerical simulation, in which we allow the pre-tax income distribution to be either given exogenously or determined endogenously.     

On the power of poverty orderings

This paper investigates the possibility of increasing the ordering power of additively separable poverty measures beyond the condition of second degree stochastic dominance by considering third degree stochastic dominance. For a fixed poverty line, the ordering power can be significantly enhanced by using the third degree criterion. For a range of poverty lines, the marginal power of the third degree criterion over the second degree depends critically upon the lower bound of the range; if the lower bound poverty line is arbitrarily close to zero, the two criteria coincide. The implications of a strong version of the transfer sensitivity axiom are also considered. Received: 20 November 1995/Accepted: 16 February 1998     

Identifying the Effects of Income on Children's Development Using Experimental Data

Prior research suggests that poverty can be detrimental to low‐income children's development. Is this relation capturing the effects of poverty or the effects of other characteristics of low‐income families associated with poverty? Can low‐income children benefit from increases in income? In this paper, an instrumental variables estimation strategy is used with data on nearly 900 children from a random assignment evaluation of a pilot welfare reform program in Minnesota in order to answer these questions and to identify the causal effects of income on children's development. There are some suggestions that increased income improves the development of low‐income children, at least with regard to their school engagement and positive social behavior. Results are discussed with regard to their implication for analysis, as well as research and policy.     

Distributional Effects of FDI: How the Interaction of FDI and Economic Policy Affects Poor Households in Bolivia

This article provides a CGE analysis of the medium to long‐run impact of FDI inflows on poverty and income distribution in Bolivia. The simulation results suggest that FDI inflows enhance economic growth and reduce poverty. However, the income distribution typically becomes more unequal. In particular, FDI widens disparities between urban and rural areas. The Bolivian government may promote the growth‐enhancing and poverty‐alleviating effects by overcoming labour‐market segmentation and providing complementary public investment in infrastructure. But simulated policy reforms or alternative productivity scenarios are hardly effective in reducing the economic divide.     

Are income poverty and perceptions of financial difficulties dynamically interrelated?

An individual’s economic ill fare can be assessed both objectively, looking at one’s income with reference to a poverty line, or subjectively, on the basis of the individual’s perceived experience of financial difficulties. Although these are distinct perspectives, income poverty and perceptions of financial difficulties are likely to be interrelated. Low income (especially if it persists) is likely to negatively affect perceptions of financial difficulties and, as recently suggested by the behavioural economics literature, (past) subjective sentiment may in return influence individual’s income generating ability and poverty status. The aim of this paper is to determine the extent of these dynamic cross-effects between both processes. Using Luxembourg survey data, our main result highlights the existence of a feedback effect from past perceived financial difficulties on current income poverty suggesting that subjective perceptions can have objective effects on an individual’s behaviour and outcomes.     

A Family of Correlation Coefficients Based on the Extended Gini Index

The extended Gini is a family of measures of variability which is mainly used in the areas of finance and income distribution. Each index in the family is defined by specifying one parameter, which reflects the social evaluation of the marginal utility of income. The higher the parameter, the more weight is attached to the lower portion of the cumulative distribution, reflecting higher concern for poverty. In this paper we list and investigate the properties of the equivalents of the correlation coefficient that are associated with the extended Gini family. In addition, we show that the extended Gini of a linear combination of random variables can be decomposed, in a way which is equivalent to the decomposition of the variance, with, in addition, terms that reflect additional properties of the random variables. The implication of these properties is that any decomposition that is performed with the coefficient of variation can be replicated by an infinite number of indices that are based on the Extended Gini coefficient.     

Marriage and the economic status of women with children

Marriage is positively correlated with income, and women with children are much less likely to be in poverty if they are married. Selection into marriage makes it difficult to assess whether these correlations represent a causal effect of marriage. One instrument for marriage proposed in past research is the gender of a woman’s first child. We find that women who have a boy first are about 0.33 percentage points more likely to be married at any point in time. This effect operates through both increasing the probability that unmarried mothers marry the child’s father and reducing the probability of divorce. We also find that women whose first child is a boy experience higher levels of family income and are less likely to receive welfare income, be below the poverty line, and receive food stamps. Estimates using child gender as an instrumental variable for marriage suggest that marriage plays a large causal role in improving the economic well-being of women with children and that these effects are largest among women at the lower end of the income distribution.     

Accounting for income distribution trends: A density function decomposition approach

This paper develops methods for decomposing changes in the income distribution using subgroup decompositions of the income density function. Overall changes are related to changes in subgroup shares and changes in subgroup densities, where the latter are broken down further using elementary transformations of individual incomes. These density decompositions are analogous to the widely-used decompositions of inequality indices by population subgroup, except that they summarize multiple features of the income distribution (using graphs), rather than focusing on a specific feature such as dispersion, and are not dependent on the choice of a specific summary index. Nonetheless, since inequality and poverty indices can be expressed as PDF functionals, our density-based methods can also be used to provide numerical decompositions of these. An application of the methods reveals the multi-faceted nature of UK income distribution trends during the 1980s.     

Distributive effects of benefits and taxes

In light of the growing federal deficit, pressure is mounting to cut federal spending. If the budget for social security programs is cut, who will suffer? This article presents the results of a study that investigated the degree to which taxes and public income transfers change the level of income, the degree of inequality in income distribution, and the poverty rates of various demographic groups. Major findings are that public income transfers are more powerful than taxes in equalizing the income distribution and that poverty reduction through non-means-tested transfer programs is more effective among elderly people, white people, and people in married-couple families, whereas poverty reduction through means-tested transfer programs is more effective among nonelderly people, black people, and people in female-headed families. Implications for social work practice are discussed.     

Analysing the effects of tax-benefit reforms on income distribution: a decomposition approach

To assess the impact of tax-benefit policy changes on income distribution over time, we suggest a methodology based on counterfactual tax-benefit simulations. Changes in inequality/poverty indices are decomposed into three contributions: changes in the tax-benefit structure, changes in nominal levels of market incomes and tax-benefit money parameters, and all other changes, including shifts in market income inequality and demographic composition. The policy effect can be evaluated conditionally on base-period data or end-period data; it is also possible to average the two measures, which corresponds to an application of the Shapley value method as reinterpreted by Shorrocks (Decomposition Procedures for Distributional Analysis: A Unified Framework Based on the Shapley Value, University of Essex and Institute for Fiscal Studies, Wivenhoe Park, 1999). The decomposition is used to quantify the relative role of policy changes on inequality/poverty trends in France and Ireland in the 1990s. When end-period data are not available, e.g., for forward looking analysis of possible reforms, the base weighted decomposition helps to extract an absolute measure of the impact of tax-benefit changes on income distribution as evaluated against a distributionally neutral benchmark; in our application, it is not significantly different from the policy effect stemming from the Shorrocks-Shapley decomposition. Estimates of this type are derived to assess recent policy changes in twelve European countries.     

Survey nonresponse and the distribution of income

The paper examines the distributional implications of selective compliance in sample surveys, whereby households with different incomes are not equally likely to participate. Poverty and inequality measurement implications are discussed for monotonically decreasing and inverted-U compliance-income relationships. We demonstrate that the latent income effect on the probability of compliance can be estimated from information on response rates across geographic areas. On implementing the method on the Current Population Survey for the U.S. we find that the compliance probability falls monotonically as income rises. Correcting for nonresponse appreciably increases mean income and inequality, but has only a small impact on poverty incidence up to poverty lines common in the U.S. Martin Ravallion: Corresponding author.     

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 and poverty impacts of different income growth patterns, and of redistributive programmes, leaky or not, which are briefly discussed.     

Kernel density estimation on grouped data: the case of poverty assessment

Grouped data have been widely used to analyze the global income distribution because individual records from nationally representative household surveys are often unavailable. In this paper we evaluate the performance of nonparametric density smoothing techniques, in particular kernel density estimation, in estimating poverty from grouped data. Using Monte Carlo simulations, we show that kernel density estimation gives rise to nontrivial biases in estimated poverty levels that depend on the bandwidth, kernel, poverty indicator, size of the dataset, and data generating process. Furthermore, the empirical bias in the poverty headcount ratio critically depends on the poverty line. We also undertake a sensitivity analysis of global poverty estimates to changes in the bandwidth and show that they vary widely with it. A comparison of kernel density estimation with parametric estimation of the Lorenz curve, also applied to grouped data, suggests that the latter fares better and should be the preferred approach.     

Learning from your neighbor: tax-benefit systems swaps in Latin America

Over the last decades, Latin American countries have experienced a noticeable decrease in income inequality. While this trend is mainly associated with a decline in wage inequality, progressive reforms of the tax-benefit systems of the region may have played a role. While redistributive systems in Latin America are still in their infancy, they are constantly expanding and do so at different pace in the region. To investigate this point in a comparative way, the present study exploits newly developed tax-benefit microsimulation models for Ecuador and Colombia. These two neighboring countries show contrasted situations in terms of income distribution and we characterize the extent to which this difference is explained by different tax-benefit systems. The comparative nature of our microsimulation models allows us to swap tax-benefit systems between countries to produce counterfactual simulations whereby the system of a country is applied to the population of the other. In this way, we can decompose the total country difference in income distribution to extract the role of different tax-benefit policies. We confirm that the Ecuadorean system is more redistributive and quantify the difference: if the Ecuadorean system was applied to the Colombian population, the Gini coefficient would be reduced by 1.7 points in Colombia. Headcount poverty would decrease by around 10% and the intensity of poverty by up to 14.7%. This analysis contributes to the recent literature on the redistributive role of tax-benefit systems in Latin America and highlights the role of microsimulation techniques to show how countries in the region can learn from each other in order to improve social protection and reduce income inequality.     

Measuring poverty without the Mortality Paradox

Under income-differentiated mortality, poverty measures reflect not only the “true” poverty, but, also, the interferences or noise caused by the survival process at work. Such interferences lead to the Mortality Paradox: the worse the survival conditions of the poor are, the lower the measured poverty is. We examine several solutions to avoid that paradox. We identify conditions under which the extension, by means of a fictitious income, of lifetime income profiles of the prematurely dead neutralizes the noise due to differential mortality. Then, to account not only for the “missing” poor, but, also, for the “hidden” poverty (premature death), we use, as a fictitious income, the welfare-neutral income, making indifferent between life continuation and death. The robustness of poverty measures to the extension technique is illustrated with regional Belgian data.