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).

Measuring Poverty (8): Deep Poverty

Most systems for measuring poverty use a so-called poverty rate or poverty line (that’s the case in the U.S. for instance, or in the UN’s Millennium Development Goals). That’s a level of income (or consumption etc.) which is considered to be the minimum that’s necessary for a decent human life and for the satisfaction of basic needs. These systems are also called “headcount” measures of poverty: they simply count how many people fall below the fixed point that determines the difference between poverty and non-poverty.

You can see the problem coming: according to these systems, you’re either poor or you ain’t. They just tell us how many people are poor, not how poor they actually are. This is a big problem in developed countries that use such poverty measurement systems. The poverty rates in those countries are rather high in dollar terms. For example, the thresholds in the U.S. are, as of 2008:

  • One adult: $11,200 annual income, not including the EITC or non-cash benefits (Food Stamps, Medicaid, housing assistance, employer health-insurance contributions, etc.), and including taxes
  • Two adults: $14,400
  • One adult, two kids: $17,300
  • Two adults, two kids: $21,800.

By “rather high” I don’t mean to say that the people under those poverty lines aren’t really poor and that the U.S. measurement system is too generous (if anything, it’s the contrary). What I want to say is that in developed countries, people need a substantial income in order to escape poverty. If you want a job, you’ll probably need a car, a phone, internet connection, child care etc. If you want a place to live, you’ll need to spend a huge amount of money on a house, and so on. Poverty lines in developed countries are therefore not so low that being poor means being on the brink of starvation. They are set at such a level that being poor means being unable to afford a job, quality housing, healthcare and education.

Given the fact that poverty rates are rather high, there’s a lot of space below them. Hence, you have different kinds of poor people: there are those who have a job and an income, albeit a rather low one, but who struggle to survive because of their expenses; and there are those who just live on the street. You have people who are poor for some years and people who are poor their entire lives.

All these people are equally poor in the measurement system we’re discussing here. This system doesn’t provide data on the distance from the poverty line, or, in other words, on the depth of poverty. In the worst case, people who are already poor according to the system could become much poorer, without any change in the headcount of poverty. If the 13% or so of Americans who are currently under the poverty line all became homeless beggars, you wouldn’t see a change in U.S. poverty statistics.

In order to solve this problem, people have come up with the concept of the poverty gap (incidence * depth of poverty): the mean distance separating the population from the poverty line (with the non-poor being given a distance of zero), expressed as a percentage of the poverty line (see also here). Unfortunately, this hasn’t become a very popular number. It’s probably too complicated. A clear and simple poverty line is much more appealing yet deficient.

More post on the problems of poverty measurement are here.

Measuring Poverty (7): Different Types of Poverty

I already mentioned the obvious but consequential fact that poverty measurement depends on the choice of the type of poverty you want to measure. Definitional issues are always important, but when it comes to poverty the choice of a definition of poverty determines who will benefit from government benefits and who won’t. For example, in the U.S. you’re poor when you’re income is below a certain poverty line. If that’s the case, you’re eligible for certain benefits. So poverty is a function of income.

1. Insufficient income

Usually, and not only in the U.S., poverty is indeed understood as insufficient income (preferably post-tax and post-benefits). Measuring poverty in this case means

  1. determining a sufficient level of income (sufficient for a decent human life); this is usually called a “poverty line” or “poverty rate”
  2. measuring actual income
  3. counting the number of people who have less income than the sufficient level.

There are some problems with this measurement system or this choice of type of poverty. Actual income levels are notoriously difficult to measure. People have a lot of informal income which they will not disclose to people doing a survey. Likewise, there is tax evasion and income in kind (market based or from government benefits, e.g. social housing), and material or immaterial support by local social networks. None of this is included correctly if at all in income measurement, leading to an overestimate of poverty. Another disadvantage of income based measurements: they neglect people’s ability to borrow or to draw from savings in periods of lower income. Again, this overestimates poverty (although one could say that it just estimates it a bit too early, since borrowing and eating up savings can lead to future poverty).

2. Insufficient consumption

Because of these problems, some countries define poverty, not by income levels, but by consumption levels. Measuring poverty in this case means

  1. determining a sufficient level of consumption (sufficient for a decent human life)
  2. measuring actual consumption
  3. counting the number of people who consume less than the sufficient level.

However, this measurement isn’t without problems either. As is the case for income levels, actual consumption levels are difficult to measure. How much do people actually consume? And what does it mean “to consume”? Is it calorie intake? Is it financial expenses? Or something else perhaps? Consumption levels are also deceiving: people tend to smooth their consumption over time, even more so than their income. If they face a financial crisis because of unemployment, bad health, drought etc. they will sell some of their assets (their house for instance) or take a loan. If you determine whether someone is poor on the basis of consumption levels, you won’t consider people dealing with a crisis as being poor because they continue to consume at the same levels. However, because of loans or the sale of assets, they are likely to face poverty in the future. They may also shift their diet away to low quality food, taking in the same amount of calories but risking their health and hence their future income. Similarly, they may be forced by their crisis situation to delay health expenditures in order to smooth consumption, with the same long term results.

And even if you manage somehow to measure consumption, you’re still faced with the problem of the threshold of sufficient consumption: that’s hard to determine as well. Consumption needs differ from person to person, depending on age, gender, occupation, climate etc.

3. Direct physical measures of real consumption

Rather than trying to measure total income or consumption, you can choose to measure consumption of certain specific physical items, and combine that with some easy to measure elements of standard of living, such as child mortality or education levels. It’s possible to argue that poverty isn’t an insufficient level of overall income or consumption, but instead the absence of certain specific consumption articles. People are poor if they don’t have a bicycle or a car, a solid floor, a phone etc. Or when their children die, can’t go to school or are undernourished. These items or indicators are relatively easy to measure (for example, there’s the Demographic and Health Survey). While they may not tell us a lot about relative living standards in developed countries (where few children die from preventable diseases for instance), they do provide poverty indicators in developing countries.

The OECD has done a lot of good work on this. They call it “measuring material deprivation“. It’s the same assumption: there are certain consumer goods and certain elements of living standard that are universally considered important elements of a decent life. The OECD tries to measure ownership of these goods or occurrence of these elements, and when people report several types of deprivation at the same time, they are considered to be poor.

Take note that we’re not talking about monetary measures here, contrary to income and overall levels of consumption. Sometimes, all that has to be measured is a “yes” or a “no”. Which of course makes it easier.

Unfortunately, not easy enough. This type of poverty measurement has its own drawbacks. Measures of material deprivation often fail to distinguish between real deprivation and the results of personal choices and lifestyles. Some people can’t have a decent life without a car or a solid floor; others voluntarily choose not to have those goods. It’s likely that only the former are “poor”. Furthermore, since these measurements are often based on surveys, there are some survey related problems. The really poor may be systematically excluded from the survey because we can’t find them (e.g. the homeless). These surveys measure self-reported poverty, and self-reported poverty can be affected by low aspirations or habit. People may also be ashamed about their poverty and hence not report it correctly.

Conclusion

There isn’t a perfect system for poverty measurement. And that has a lot to do with the fact that poverty is an inherently vague concept. It really shouldn’t be a surprise that people choose different definitions and types, and hence different measurement methods that all provide different data. There’s no “correct” definition of poverty, and hence no correct poverty measure.

More posts in this series on the difficulties of poverty measurement.

Measuring Poverty (6): The Poverty Line in the U.S.

The poverty rate or poverty line in the U.S. is based on a system pioneered by Mollie Orshansky in 1963. In the 1960s, the average US family spend one third of its income on food. The poverty line was calculated by valuing an “emergency food” budget for a family, and then multiplying that number by 3. (Some more data here).

This results in a specific dollar amount that varies by family size but is the same across the U.S. (the amounts are adjusted for inflation annually). To determine who is poor, actual family income is then compared to these amounts. Obviously, if you’re under, you’re poor.

Amazingly, this system hasn’t changed a lot since the 1960s, yet it suffers from a series of measurement problems, resulting in either an over- or underestimation of the number of families living in poverty. The problems are situated both in the calculation of the poverty rates and in the calculation of the income that is subsequently compared to the rates:

  • Obviously, the system should take regional differences in the cost of living, especially in housing, into account. It doesn’t.
  • As already apparent from the image above, a family today spends relatively less on food and more on housing, health care and child care etc. yet the poverty line is still dollars for emergency food times 3. So the question is: should the system take today’s spending patterns into account? We would have to know which it is: 1) Either the increased spending on non-food items has occurred because people can now afford to spend more on such items. 2) Or the increased spending on non-food items has occurred because these items got disproportionately more expensive (housing for instance) or because there wasn’t really any need to buy those items in the old days. Only if 2) is the case should that have an influence on the poverty line. And I think that to some extent it is the case. Child care for instance has become a necessity. In the 1960s, many mothers didn’t go out and work. Now they do, and therefore they have to pay for child care. Those payments should be deducted from income when measuring disposable income and comparing it to the poverty line. The same is true for cars or phones. Today you can’t really have a job without them so they’re no longer luxuries. A society would show very little ambition if it continued to designate the poor as those who have to wash by hand, read with candlelight, and shit in a hole in the floor. In fact, what I’m advocating here is some kind of relative concept of poverty. I’ll come back to that later. All I can tell you now is that this isn’t without complications either.
  • The current poverty measurement doesn’t take into account disproportionate price rises (it merely adjusts for general inflation) and changing needs. An obvious improvement of the U.S. measurement system would be to adjust for exceptional price evolutions (such as for housing) and also to revisit the definitions of basic needs and luxuries. Hence, a better poverty measurement should subtract from income some work-related expenses, child care expenses, and perhaps also some health expenses to the extent that these have become disproportionately more expensive. But that’s not easy:

There is considerable disagreement on the best way to incorporate medical care in a measure of poverty, even though medical costs have great implications for poverty rates. But costs differ greatly depending upon personal health, preferences, and age, and family costs may be very different from year to year, making it hard to determine what exactly should be counted. Subtracting out-of-pocket costs from income is one imperfect approach, but if someone’s expenses are low because they are denied care, then they would usually be considered worse off, not better off. (source)

  • Another problem: the current poverty rate doesn’t take all welfare benefits into account. Income from cash welfare programs counts, but the value of non-cash benefits such as food stamps, school lunches and public housing doesn’t (because such benefits weren’t very common in the 1960s). Those benefits successfully raise the standard of living for poverty stricken individuals. There’s a bit of circular reasoning going on here, because the poverty rate is used, i.a., to decide who gets benefits, so benefits should not be included. But if you want to know how many people are actually poor, you should consider benefits as well because benefits lift many out of poverty.
  • The poverty measure doesn’t include some forms of interests on savings or property such as housing.
  • The poverty measure doesn’t take taxes into account, largely because they didn’t affect the poor very much in the 1960s. Income is counted before subtracting payroll, income, and other taxes, overstating income for some families. On the other hand, the federal Earned Income Tax Credit isn’t counted either, underestimating income for other families.
  • And there’s also a problem counting the effects of cohabitation and co-residency, overestimating poverty because overestimating expenses.

Because the poverty measurement disregards non-cash benefits and certain tax credits, it fails to serve its purpose. Poverty measurement is done in order to measure progress and to look at the effects of anti-poverty policies. Two of those policies – non-cash benefits and certain tax credits – aren’t counted, even though they reduce poverty. So we have a poverty statistic that can’t measure the impact of anti-poverty policy… That’s like measuring road safety without looking at the number of accidents avoided by government investment in safety. Since the 1970s, the U.S. government implemented a number of policies that increased spending for the poor, but the effects of this spending were invisible in the poverty statistics.

This had a perverse effect: certain politicians now found it easy to claim that spending on the poor was ineffective and a waste of money. It’s no coincidence that trickle down economics became so popular in the 1980s. The poverty measurement, rather than helping the government become more effective in its struggle against poverty, has led to policies that reduced benefits. Of course, I’m not saying that poverty reduction is just a matter of government benefits, or that benefits can’t have adverse effects. Read more here.

Fortunately, the US Census Bureau has taking these criticism to heart and has been working on an alternative measure that counts food stamps and other government support as income, while also accounting for child-care costs, geographic difference etc. First results show that the number of poor is higher according to the new measurement system (it adds about 3 million people). For some reason, I think the old system has still some life in it.

Some details of the new measurement:

when you account for the Earned Income Tax Credit the poverty rate goes down by two points. Accounting for SNAP (food stamps) lowers the poverty rate about 1.5 points. … when you account for the rise in Medical Out of Pocket costs, the poverty rate goes up by more than three points. (source)

More posts about problems with poverty measurement are here.

Measuring Poverty (2): Some Problems With Poverty Measurement

The struggle against poverty is a worthy social goal, and the absence of poverty is a human right. But poverty is also an obstacle to other social goals, particularly the full realization of other human rights. A necessary instrument in poverty reduction is data: how many people suffer from poverty? Without an answer to that question it’s very difficult to assess the success of poverty reduction policies (such as development aid).

And that’s were the problems start. There’s some uncertainty in the data. The data may not reflect accurately the real number of people living in poverty. There are definition issues – what is poverty? – that may reduce the accuracy of the data or the comparability between different measurements of poverty (or between different measurements over time), and there are issues related to the measurements themselves. I’ll focus on the latter for the moment.

Poverty is often measured by way of surveys. These surveys, however, can be biased because of

  1. sample errors: underreporting of the very rich and the very poor (more on sample errors here), and
  2. reporting errors: failure of the very rich and the very poor to report accurately.

The rich are less likely than middle-income people to respond to surveys because they are less accessible (their houses for instance are less accessible). In addition, when they respond, they may tend to underreport a larger fraction of their wealth as they have more incentives to hide (for tax reasons for example).

The very poor may also be inaccessible, but for other reasons. They may be hard to interview when they don’t have a fixed address or an official identification. In poor countries, they may be hard to find because they live in remote areas with inadequate transportation access. And again, when they report, it may be difficult to estimate their “wealth” because their assets are often in kind rather than in currency.

Because we can have underreporting of the two extremes on the wealth distribution, we believe that income distribution is more egalitarian than it really is. Hence we underestimate income inequality and relative poverty.

But apart from relative poverty we also underestimate absolute poverty since we’re often unable to include the very poor in the reporting for the reasons given above. By “cutting off” the people at the poor end of the distribution, it seems like most people are middle class and society largely egalitarian.

However, absolute poverty can also be overestimated: if the poor respond, we may fail to accurately assess their “wealth” given that much of it is in kind. And it’s unlikely that these two errors – underestimation and overestimation – cancel each other out.

These and other problems of poverty measurement make it difficult to claim that we “know” more or less precisely how many poor people there are, but if we make the same errors consistently we may be able to guess, not the levels of poverty, but at least the trends: is poverty going up or down?