Measuring Poverty (16): The Capabilities Approach and the Unstraightening of the Poverty Line

We usually define poverty as a level of income or financial assets below a certain “poverty line”. This poverty line is set, often implicitly, at a level that is supposed to make the difference between decent survival and a life unworthy of human beings. The line is typically a single line, identical across all individuals – or even across nations. The best example is the $1 a day line. This is a single, universal line, adjusted only for purchasing power parity. Many national poverty lines are also fixed and identical for all citizens.

The problems with these fixed and uniform lines have been noticed by many, notably by Amartya Sen. According to Sen – and he’s right I think – being poor means being unable to achieve certain minimally satisfactory states of being and doing, for example the state of being sufficiently nourished, of being mobile, of being free of disease and ignorance, of being sheltered against the forces of nature etc. Poverty is about what people are or are not able to do and about who they are able to be. Poverty is capability-deprivation.

A poverty line only makes sense if it’s set at an amount of money, income or resources that is sufficient to guarantee the required capabilities. A first problem: it’s not at all clear that existing poverty lines are indeed set at a level sufficient to guarantee this. $1 a day in particular seems low, intuitively. Of course there are pragmatic reasons to set the line at a low level (one has to make priorities in life and help the worst off first). But then you’ll have a hard time calling it a poverty line, given the definition of poverty as the inability to achieve certain minimally satisfactory states of being and doing. Call it a survival line instead.

A second, and more serious problem arises from the fact that poverty lines are fixed and uniform. People, however, are obviously not uniform. Different people require different things in order to achieve the same capabilities. A pregnant women or a young mother needs more nutritional resources than the average person in order to achieve the state of being sufficiently nourished. A physically handicapped person needs more resources to achieve the capability of being mobile. If you focus on the average person – which is what you do with a uniform poverty line – then you’ll fail to identify some as being poor, while erroneously identifying others as being poor. And the environment also plays a role. A person living in unsanitary conditions may be forced to drink infected water. This affects his or her calorie absorption, implying a larger than average amount of food necessary to be sufficiently nourished. Cold weather means more effort to protect against the environment. And so on.

Identical capabilities require different levels of resources or income. A single, fixed poverty line obscures this reality. The only good poverty line is individually specific. However, that’s completely impractical. Differentiation across demographic groups, regions, occupations, lifecycle etc. might be more feasible, but at the cost of simplicity. Be that as it may. I would already be happy with increased awareness that there is indeed a problem. Talk of a “line” reduces this awareness, but I’m realistic enough to understand the appeal of something as simple as a line.

More posts in this series are here.

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Measuring Poverty (15): A Common Misconception About Relative Poverty

Yesterday, I had a short email exchange with Tim Harford, in which I reacted to one of his claims in this article, more specifically the claim that the use of a relative notion of poverty in poverty measurement implies that poverty will always be with us:

Eurostat, the European Union’s statistics agency, … defines the poverty line as 60 per cent of each nation’s median income. (The median income is the income of the person in the middle of the income distribution.)

This has an unfortunate consequence: poverty is permanent. If everyone in Europe woke up tomorrow to find themselves twice as rich, European poverty rates would not budge. That is indefensible. Such “poverty” lines measure inequality, not poverty.

This argument against relative poverty is as common as it is mistaken. Here’s my email to Tim:

I read your article on poverty measurement a moment ago, and I wanted to object. You say that using a relative poverty measurement of income below 60% of median income makes poverty “permanent”. It does not. True, someone with an income of 61% of the median does not suddenly become poor because the median person receives a pay rise. But it’s also true that it’s perfectly doable – mathematically if not in reality – to raise every single poor person’s income above 60% of the median without changing the median. Poverty is only permanent when one would use 60% of the average as threshold, but no one proposes such a foolish thing, fortunately.

In fairness to Tim, his article does list some advantages of relative poverty and he qualified his views in our email correspondence.

More posts in this series are here.

Measuring Poverty (14): Measuring Income Inequality

Income inequality may or may not be the best definition of poverty,  but it’s certainly one that is often used. In many European countries, you’re counted as poor when your income is below 50% or so of the median income. Maybe this is the wrong way to measure poverty, but if you use absolute measures for poverty (such as a basic income, minimum consumption etc.) you’ll also face some problems. So it’s worthwhile to examine some of the usual methods for measuring income inequality and see how they hold up, while at the same time bracketing the discussion about poverty as either absolute deprivation or unequal distribution.

Methods for measuring income inequality

The Gini coefficient is the most widely used. It’s based on the proportion of the total income of a population that is cumulatively earned by a % of the population; a value of 0 expresses perfect equality where everyone has equal shares of income and a value of 1 expresses maximal inequality where only one person has all the income. A low Gini coefficient indicates therefore a more equal distribution. (The complete formula is here).

A disadvantage of the Gini measure is that it doesn’t capture where in the distribution the inequality occurs: is a society unequal because the top 1% has astronomically high incomes, because the poor are very poor, because there is practically no middle class, or because of some other reason?

Other measures are

  • the ratio of the incomes of the top 10% (best paid) to the bottom 10% (worst paid)
  • the proportion of a population with income less than 50% of the median income
  • a population may be split into segments, e.g. quintiles or deciles, and each segment’s income share is then compared to each other segment’s (for example, the top 10% of the population – “top” in income terms – has x % of total income)
  • some other measures are here.

These different measures can give contradictory numbers: two societies with the same Gini score can have different ratios of top-bottom, top-middle or middle-bottom incomes (see an example here). Hence, no single measure will tell us the last word about inequality in a society.

What is income?

The focus of all these measurement systems is income, but we should first decide what to count as income. Income doesn’t have to be cash or currency. A farmer in a poor country who grows his own products has non-cash income. Perhaps public services such as healthcare or education should count as income. And how about tax reductions, tax refunds, government benefits such as unemployment insurance, food stamps and various vouchers?

All those forms of non-cash or non-labor income are important when measuring income inequality because the poor profit disproportionately from those non-cash or non-labor related forms of income. Hence, including them in total income can make a large difference in income inequality numbers. (Higher income groups may have less or different tax refunds and their education may represent a smaller portion of their total income – the returns of their education may of course be higher, but those returns are typically cash based in the sense that they lead to higher labor compensation).

We should also decide if we want to use income before or after taxation; depends if we want to measure the effectiveness of redistribution or simply gross inequalities. And what about capital gains, imputed house rents from home ownership, inheritance etc. In general, how should wealth be included in income? Or shouldn’t it be?

How do we measure income?

Once we’ve solved the difficult problem of defining income, we’re still left with the practical problem of measuring it. Most cash income is captured in tax return data, but not all, and not equally well in all countries. Sometimes, you’ll need to use consumption data as a proxy for income data, or surveys about living standards. “Informal” income typically does not show up in tax data, but does in consumption data.

Another problem with measures of inequality is that they may be contaminated by notions of fairness. Some deliberately design their measurement system in such as way that inequalities look bigger than they actually are. For example, they use pre-tax inequalities because those are often larger than post-tax inequalities – a lot of tax systems are redistributive towards the poor (e.g. progressive taxation systems). Or they focus on income inequality when consumption inequality may have diminished. Others may mistakenly deduce evaluations of fairness or injustice from the simply fact of income distributions and forget that measures of income inequality are silent about who is on which side of the divide. If person A in a two person economy has twice the income of person B, then the measurement of inequality would be absolutely the same when B switches places with A. Measures of income inequality say nothing about who deserves what, about how income has been acquired, about whether some occupations should yield higher compensation (for example because we want the right incentives), or about how income should ideally be distributed.

And then there is the opposite mistake: assuming that income inequality is always necessary and just because it’s the automatic result of the fact that people have different levels of human capital and productive abilities. This is a mistake because it ignores a number of facts: no one has ever been able to prove that some abilities or occupations deserve higher wages from a moral point of view, and a lot of inequality is the result not of different abilities or efforts but of differences in luck and connections. Hence, fairness remains a legitimate concern. Contrary to the “left-wing mistake”, the “right-wing mistake” will not distort the measurement of inequality: if you believe inequality is not a problem you hardly have a reason for measuring it, let alone distort the measurement.

What I want to stress is how difficult it is to measure income inequality and how many mistakes we can make. This doesn’t mean that the numbers are rubbish. We should just be careful when drawing sweeping conclusions, that’s all.

Something more about the causes of income inequality, rather than the measurement of it, is here.

Measuring Poverty (12): The Experimental Method

The so-called experimental method of poverty measurement is akin to the subjective approach. Rather than measuring poverty on the basis of objective economic numbers about income or consumption the experimental method uses people’s subjective evaluation of living standards and living conditions. But contrary to the usual subjective approach it’s aim is not to ask people directly about what poverty means to them, about what they think is a reasonable minimum level of income or consumption or a maximum tolerable level of deprivation in certain specific areas (food, health, education etc.). Instead, it uses experiments to try to gather this information.

For example, you can set up a group of 20 people from widely different social backgrounds and some of them may suffer from different types of deprivation, or from no deprivation at all. The group receives a sum of money and has to decide how to spend it on poverty alleviation (within their test group or outside of the group). The decision as to who will receive which amount of funding targeted at which type of deprivation has to be made after deliberation and possibly even unanimously.

The advantage of this experimental approach, compared to simply asking individual survey respondents, is that you get a deliberated choice: people will think together about what poverty means, about which types of deprivation are most important and about the best way to intervene. It’s assumed that such a deliberated choice is better than an individual choice.

More posts in this series are here.

Measuring Poverty (11): The Subjective Approach

Usually, we measure poverty on the basis of objective numbers about income or consumption. Income or consumption levels are put on a continuum from lowest to highest and somewhere along the continuum we put a threshold that indicates the difference between poor and non-poor. For example, the Indian government uses a consumption threshold of 2,400 calories a day in rural areas and 2,100 in urban areas. The World Bank uses an income threshold of one dollar a day (corrected for purchasing power).

There are numerous disadvantages to these objective approaches. One is the inevitably arbitrary positioning of the threshold. One dollar a day, even after correction for purchasing power, means different things to different people in different areas, circumstances, groups etc. Calorie intake also means different things to different people, depending on people’s way of life etc. Moreover, income levels are notoriously difficult to measure (poor people in particular have a lot of informal income, e.g. “income” coming from all sorts of assistance from relatives etc.). Consumption as well is a difficult measure: it doesn’t necessarily have to mean just calorie intake for example. Poverty can mean a lack of non-food consumption. And if you focus on calorie levels after all, you’ll miss the issue of the quality of the food.

Also the third most common approach to poverty measurement suffers from some disadvantages. This approach, also called the multidimensional approach, tries to assess to what extent people suffer from a series of different types of deprivation: do they have access to water, to electricity, are they literate, malnourished etc. Rather than purely quantitative these measurements can be qualitative: a binary yes/no is often enough. Unfortunately, also this measurement system has some drawbacks: it fails to distinguish between deprivation and choice; there’s necessarily a level of arbitrariness in the determination of the “basic needs” or forms of deprivation that are measured; and these needs are often overly general, obscuring some very specific needs for some people in some areas or groups.

That’s why people have been searching for alternative measures of poverty. One such alternative is the use of surveys that ask people about poverty. You could ask people what they believe is “the smallest amount of money a family needs each week to get along in this community”, “what is the level of income below which families can’t make ends meet” etc. That would remove some of the arbitrariness of the cutoff line between poor and non-poor, and putting that decision in the hands of the people rather than the scientists.

Or you could also present people with evocative descriptions of different family situations, of types of families according to their level of income or consumption or according to the type of deprivation. People would then have to decide for every family situation what they believe the standard of living is and which situation can be described as “poverty”. That would specify what poverty means to people. And what it means to people is much more important than what it means to researchers and statisticians.

A disadvantage of this subjective approach is the wellknown effect that people’s income levels affect their judgments about income adequacy. In short, relatively rich people overestimate the level of income inadequacy. A solution to this problem could be to ask only poor respondents about poverty, on the reasonable assumption that poor people are the best experts on poverty. But that’s a circular reasoning: you already think you know what poverty is before you start asking about it. Since you focus only on the poor, you’ve already decided what poverty is.

An advantage of the subjective approach is that researchers don’t have to list basic needs or types of deprivation in order to assess what poverty is; people tell you what poverty is. There’s also no need for researchers to specify regionally or socially undifferentiated and general cutoff levels of income or consumption below which people are considered to be poor.

Measuring Poverty (10): Multidimensional Poverty

Poverty can be many different things. It can be different things to different people in different countries or circumstances. It can mean one thing for people in Africa and another for people in the favelas in Rio, and still another for those in the inner-cities in the U.S. It’s probably different for men, women and children. It can be absolute deprivation or relative poverty (i.e. inequality). It can be insufficient income or insufficient consumption. It can be a lack of one thing or another. For some people it means inadequate healthcare, for others it means insufficient water. It can be physical suffering or the stress inherent in insecurity. It can be malnutrition or a lack of self-esteem. It can be illiteracy or child mortality. Etc.

Most poverty measurement systems try to keep it simple. The most common systems just measure income. Poverty is then insufficient income (typically below $1-a-day, corrected for purchasing power; this measures the number of people incapable of buying a basic basket of commodities). That makes sense, because without sufficient income, you’re likely to experience child mortality, illiteracy, malnutrition, inequality, water shortages, stress, insecurity and all the other nasty things that come with poverty.

However, it is important to know those details of poverty. Two people who both have an income of less than one dollar a day, may experience very different consequences: one may be deprived in lots of areas, the other one maybe in just a few. One may lack good health, may be starving and may be illiterate. The other one may just be illiterate. If we want to help people, it’s important to know what the exact nature of their problem is. Which we don’t if we just focus on how much their income is.

That is why some researchers at the Oxford Poverty and Human Development Initiative at the University of Oxford have tried to come up with a so-called Multidimensional Poverty Index (MPI).

The index seeks to build up a picture of the prevalence of poverty based on the fraction of households who lack certain basic things. Some of these are material. Does a family home have a dirt or dung floor? Does it lack a decent toilet? Must members of the household travel more than 30 minutes on foot to get clean water to drink? Do they live without electricity? Others relate to education, such as whether any school-age children are not enrolled or whether nobody in the family has finished primary school. Still others concern health, such as whether any member of a household is malnourished. A household is counted as poor if it is deprived on over 30% of the ten indicators used. Researchers can then calculate the percentage of people in each country who are “multidimensionally poor”. (source)

Such a multidimensional approach has the advantage of identifying which specific aspect(s) of poverty is/are most common in certain areas or among certain groups of people. It shows how people are poor, and what contributes most to poverty in a specific place and among a specific group. This will obviously greatly enhance response capacity. Rather than just trying to generally increase income, we can target our efforts more specifically: in one area or among one group of people we know that we should focus on nutrition; elsewhere we know that we should focus on literacy for instance. The MPI also shows us how different aspects of poverty overlap: for example, how many people who are illiterate also have health problems?

If 30% of people are malnourished and 30% of children are out of school, it would be useful to know if these deprivations affect the same families or different ones. (source)

The approach also helps us to distinguish between deprivation and choice. People may actually prefer mud floors to concrete floors in some places, and don’t consider having a mud floor as a form of deprivation. It also helps to identify the depth of poverty: deprivation along a wide spectrum of indicators means that poverty is deeper.

Unsurprisingly, the results of the MPI are substantially different from traditional poverty measurements:

Also the totals are different:

About 1.7 billion people in the countries covered – a third of their entire population – live in multidimensional poverty, according to the MPI. This exceeds the 1.3 billion people, in those same countries, estimated to live on $1.25 a day or less, the more commonly accepted measure of ‘extreme’ poverty. (source)

One of the disadvantages of this new approach is the weighting of the different measures: there’s inevitably some arbitrariness involved. Is the death of a child equivalent to having a dirt floor? Worse? How much worse? More criticism of the MPI is here.

There’s a really cool interactive map of the MPI here.

Measuring Poverty (9): Absolute and Relative Poverty Lines

There are many ways you can measure how many people in a country are poor. Quite common is the use of a so-called poverty line. First you decide what you mean by poverty – for instance an income that’s insufficient to buy life’s necessities, or an income that’s less than half the average income etc. Then you calculate your poverty line – for instance the amount of income someone needs in order to buy necessities, or the income that’s half the average income, or the income of the person who has the tenth lowest income if the population was one hundred etc. And then you just select the people who are under this poverty line.

I intentionally chose these examples to make a point about absolute and relative poverty. In the U.S., people mostly use an absolute poverty line, whereas in Europe relative poverty lines are used as well. As is clear from the examples above, an absolute poverty line is a threshold, usually expressed in terms of income that is sufficient for basic needs, that is fixed over time in real terms. In other words, it’s adjusted for inflation only and doesn’t move with economic growth, average income, changes in living standards or needs.

A relative poverty line, on the other hand, varies with income growth or economic growth, usually 1-to-1 since it’s commonly expressed as a fixed percentage of average or median income. (It obviously can have an elasticity of less than 1 since you may want to avoid a disproportionate impact on the poverty line of very high and very volatile incomes. I’ve never heard of an elasticity of more than 1).

Both absolute and relative poverty lines can be criticized. Does an absolute poverty line make sense when we know that expectations change, that basic needs change (in contemporary Western societies, not having a car, a phone or a bank account can lead to poverty), and that the things that you need to fully participate in society are a lot different now than they once were? We know that people’s well-being does not only depend on the avoidance of absolute deprivation but also on comparisons with others. The average standard of living defines people’s expectations and when they are unable to reach the average, they feel excluded, powerless and resentful. Can people who fail to realize their own expectations, who lose their self-esteem, and who feel excluded and marginalized be called “poor”? Probably yes. They are, in a sense, deprived. It all depends which definition of poverty we can agree on.

It seems that people do think about poverty in this relative sense. If you compare the (rarely used) relative poverty line of 50% of median income in the U.S. with the so-called subjective poverty lines that result from regular Gallup polls asking Americans “how much they would need to get along”, you’ll see that the lines correspond quite well.

So if relative poverty corresponds to common sense, it seems to be a good measure. On the other hand, a relative poverty line means moving the goal posts for all eternity. We’ll never vanquish relative poverty since this type of poverty just moves as incomes rise. It’s even the case that relative poverty can increase as absolute poverty decreases, namely when there’s strong economic growth (i.e. strong average income growth) combined with widening income inequality (something we’ve seen for example in the U.S. during the last decades). (Technically, if you use the median earner as the benchmark, relative poverty can disappear if all earners who are below the median earner move towards the median and earn just $1 or so less than the median. But in practice I don’t see that happening).