The Supplemental Expenditure Poverty Measure: A New Method for Measuring Poverty
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A new poverty measure shows a higher rate than conventional methods, indicating 8m more Americans are considered poor.
We propose a new measure of the rate of poverty we call the Supplemental Expenditure Poverty Measure, or SEPM. It is based on total current expenditure in the Consumer Expenditure survey and treats expenditures in that survey as a measure of resources available to the household to purchase the minimum bundle necessary to meet basic needs. An augmented poverty measure based on Liquid Available Resources, which adds resources available from liquid assets and accessible, but unused, borrowing, is also presented. Our expenditure poverty measure differs from conventional income poverty measures and from consumption poverty measures in both concept and measurement, and we argue it is superior to both. We find that poverty rates using what we call our Current Expenditure measure are slightly greater than those of the most preferred income-based poverty rate produced by the Census Bureau, the Supplemental Poverty Measure (SPM). However, both have trended downward at approximately the same rate for the last 10 years. But the relative levels of our SEPM poverty rates and those of the Census income-based measures are very sensitive to the choice of threshold. Our augmented poverty measure based on Liquid Available Resources shows lower poverty rates than the SPM but we are only able to present a range of estimates of the difference, not a point estimate. At maximum, we find poverty rates to be lowered by about two percentage points.But our Current Expenditure SEPM and Liquid Available Resources SEPMshow the same decline as the Census income-based SPM quite closely. There are no available consumption poverty measures that are comparable to our SEPM, so we are not able to compare our SEPM levels or trends to such a measure…. Given the dramatic differences in the way the SIPM is constructed from the Official measure, the surprise in Figure 1 is how little they differ...Consumption poverty estimates are less standardized and differ from study to study. Those show in Figure 1 are drawn from Meyer and Sullivan (2019), which updates the estimates in Meyer and Sullivan (2012)….Table 2 illustrates the importance of the threshold by showing gross and net SEPM and SIPM poverty rates for what are called, in the literature, “Deep Poverty” and “Near Poverty.” The first is calculated as the fraction of the population which is less than 50 percent of the threshold, and the latter is calculated as the fraction of the population which is less than 150 percent of the threshold. These are generally regarded as important alternatives because the threshold itself has certain arbitrary elements in its definition, and it helps to see more of what the full distribution looks like at the bottom, not just the fraction above and below one particular point. But, for our purposes, Table 2 reveals that SEPM poverty rates are lower than those for the SIPM when looking at Deep Poverty, but much higher than those for the SIPM when looking at Near Poverty. For net poverty rates, the SEPM Deep Poverty rate is 1.5 percent compared to a 4.1 rate for SIPM Deep Poverty, while the SEPM Near Poverty rate is 32.6 percent as against the 25.5 percent for SIPM Deep Poverty. The Deep Poverty rates capture more directly the effects of possible underreporting of income, while the Near Poverty rates show how many more US households have low—but not extremely low—expenditures.
John Fitzgerald and Robert Moffitt, "The Supplemental Expenditure Poverty Measure: A New Method for Measuring Poverty,"Brookings Papers On Economic Activity, March 2022, https://www.brookings.edu/wp-content/uploads/2022/03/SP22_BPEA_FitzgeraldMoffitt_conf-draft.pdf
Core Finding, "...We implement our SEPM on the Consumer Expenditure survey data from 2004 to 2019.We find that what we call gross SEPM poverty rates—based just on total household expenditures in a period—were smaller in 2019 than those estimated with income data from the CPS. However, expenditure poverty rates depend critically on exactly where the poverty line is drawn because there is a large mass of low-expenditure households whose expenditures are just below and above the most preferred threshold used by the Census Bureau. As a consequence, for example, netting out certain costs from expenditures moves more into poverty using our SEPM expenditure measure than netting those same costs out of income, making SEPM net poverty rates higher than those using income. Also, moving the poverty line up slightly to capture those households who are “almost” poor but not quite, also makes SEPM poverty rates higher than those using income. Overall, we find that there are many more low-expenditure households in the U.S. than low-income households, in percentage terms. We also assess the ability of households to escape poverty by drawing on available liquid bank balances and by using available, but unused, credit debt to finance purchases of basic goods. Many low-income households already do that, but some do not use all the potential borrowing they could. We find that bank balances are quite small and, when counted toward ability to escape poverty, make only a small 1 percentage point difference in reducing poverty rates. But we find that available credit card borrowing could potentially lower poverty rates further by up to 2 percentage points. But these estimates are highly uncertain and much more research is needed on credit cards as an available resource over a relevant time horizon before any definite conclusion can be reached….”
The Evidence
Current Expenditure SEPM Results
“…Table 1 shows the building blocks for our SEPM poverty rate using the CE and the SIPM using the CPS for 2019. The first rows present statistics on the distributions of gross CE expenditure and gross Adjusted CPS income. In the whole population, CE mean and median expenditures are much lower than those in the CPS, but this deserves little attention because it is the lower tails of each that are relevant to poverty measurement. A key result is that the income distribution in the CPS has a much longer left-hand tail than the expenditure distribution in the CE, and the difference gets larger, the lower in the distribution one goes. The best explanation for this is simple underreporting of income in the CPS but, whatever the cause, it implies that poverty rates may differ simply because of this difference…”
“.. Figure 2 shows the two distributions graphically but in dollar terms and not percentile terms. A vertical dotted line shows the average SIPM threshold we will use to calculate poverty rates as the fraction of the distribution to the left of that line. The most important difference, which as suggested by Table 1, is that expenditures are much more concentrated in a mass just above the threshold, unlike the most dispersed income distribution. Because the density curves cross and hence neither distribution first-order stochastically dominates the other, the relative poverty rates of the SEPM and SIPM will depend on where the threshold is located. In Figure 2, it is not visually apparent whether expenditures or income have a greater fraction to the left of the line. But Table 1, showing gross SEPM and SIPM poverty rates, show that the fraction of income below the threshold, 8.8 percent of income observations, is almost identical to the fraction of expenditures, 8.7 percent. Thus the differences in the distributions of income and expenditure below the poverty line essentially cancel out….”
Trends, 2004-2019
“…Trends in Gross and Net SIPM and SEPM poverty rates from 2004 to 2019 are shown in Figure 4. We show both Net and Gross since there are some differences between them, as there were in 2019. The Gross SEPM poverty rate was approximately 11 percent in 2004, fell to about 8 percent in 2007, then rose through 2010 to about 12 percent (no doubt because of the Great Recession), and then began a gradual decline to its 2019 value of 8.7 percent (the decline coinciding with a general economic growth period in the country).The Gross SIPM poverty rate shows lower values in the 2004-2007 period, a somewhat sharper rise from 2007 to 2011, and then a sharper fall through 2019, ending at its final value of 8.8 percent, almost identical to that for the SEPM. We view these results as altering to some extent the 2019 results, for at least over the last 10 years the Gross SEPM has been below the SIPM for almost all of that period, even though both have fallen from the Great Recession peaks. When moving to the Net Poverty rates, both the SEPM and SIPM shift upward, as already discussed, and the shift upward results in a somewhat similar pattern of time trends of each over the entire 2004-2019 period. Both continue to have declined since the Great Recession, for example. However, as in 2019, the Net SEPM is above the Net SIPM, and for all years since 2009. Once again, the reason is the larger mass of expenditures just above the poverty threshold than the fraction of income observations there, so that reductions in both increase expenditure poverty rates more than income poverty rates….”
“…Figure 1 shows current estimates of the level and trend of poverty using three different measures from 1990 to 2018.The Official measure compares cash income before taxes and transfers to a threshold defined in 1963 estimated as the amount of income needed for a minimum level of food expenditure. It is held constant in real CPI-U dollars since then. It omits in-kind transfers from income, makes no adjustment for cross-area differences in the cost of living, and uses a non-standard equivalence scale. The interesting aspect of the trend in Official poverty is how little it has changed over time, despite the expectation that poverty rates should eventually decline for any absolute poverty measure. While there are clear business cycle effects, the last value is only slightly lower than that in 1990. In part this reflects the growth in wage inequality and the associated slow rate of growth of wages for unskilled workers. But its omission of taxes and transfers and in-kind benefits programs makes its poverty rates too high (taxes have declined for the low income families and transfers have grown). The Supplemental Poverty Measure which we denote as the SIPM bases its threshold on a minimum bundle composed of food, clothing, shelter, and utilities, and on a measure of how much is spent on those four goods in the lower part of its distribution. The threshold is updated over time as expenditures on those goods rise in that lower section, intended to represent changing social norms for where households are relative to others in ability to purchase that bundle. This obviates the need for a price index because the threshold is defined in nominal dollars. The income measure subtracts from gross money income an estimate of net taxes paid, which can be negative because of federal and state tax credits to lower income families, and it includes estimates of in-kind transfers received by each family (SNAP plus four others noted below). The SIPM also considers working families to incur work-related expenses, which are subtracted from income, as are child care expenses and any child support paid to a child caregiver outside the family. Somewhat more controversially, it subtracts from income a measure of medical out-of-pocket expenses, including health insurance premiums paid plus medical costs not reimbursed by insurance (Medicaid is otherwise ignored in the SIPM).8 The SIPM also deals with homeowning by using a separate threshold for homeowners with mortgages, without mortgages, and renters, on the assumption that homeowner with mortgages need more income to purchase the rest of the minimum bundle and those without mortgages need less. It also adjusts the thresholds for a state- and metro-area level price index. Given the dramatic differences in the way the SIPM is constructed from the Official measure, the surprise in Figure 1 is how little they differ. The SIPM is slightly higher in level, which is not so much because of differences in the thresholds (Fox et al., 2015) but because the subtractions from income outweigh the addition of tax credits and in-kind transfers. The two follow similar trends over time……The dramatically different shape of the consumption poverty level and trend in Figure 1 is at least partially explained by two factors. One is that the authors do not take a position on what the threshold should be and hence do not simply compare their estimates of consumption to either the Official threshold or the SPM threshold. Instead, they “anchor” their poverty measure by finding a consumption threshold that would yield the same poverty rate as the Official measure would; in figure 1, their anchoring at 2015 is shown. They update that threshold forward and backward for prices alone, thereby constructing a absolute poverty measure rate. The other is that the authors use the CPI-U-RS, which shows a lower rate of inflation than the CPI-U, and they also subtract 0.8 percentage points from it every year on the argument that the CPI-U-RS.This leads to a greater decline of poverty over time than would result from using the CPI-U or the CPI-U-RS, ceteris paribus. This measure of consumption poverty is not comparable to either the Official measure or the SIPM, nor to our measure discussed next….Our Current Resources SEPM poverty measure uses consumer expenditure from the CE as the basic building block of available resources. We do not exclude any items that might be regarded as investment or saving because those could have been used, instead, to buy the minimum bundle and hence should be included in resources. We also include all down payments on durables in our expenditure measure, because the household could have chosen not to purchase the durable and apply that expenditure toward the minimum bundle instead. We also include debt payments to the extent we can with the CE data, on the grounds that those are cash payments and are therefore liquid. We recognize that their inclusion could be objected to on liquidity grounds but, unlike service flows, they represent actual cash outlays that could in principle have been redirected toward the purchase of the minimum bundle if the debt had not been incurred in the first place.9 As we noted in the Introduction, our expenditure measure includes that made with credit cards and any drawdown of assets, but the CE does not ask the source of expenditures or whether either of those methods were used for purchases….…Because we want to make the SIPM our main poverty measure of comparison, we adopt all other methods used in that measure. We use the same thresholds as the SIPM, the same differentiation of those thresholds by homeowner and mortgage status, the same type of geographic cost-of-living adjustments, and the same family size equivalency scale. We also add to our expenditure total estimated amounts of the four in-kind transfers other than SNAP which the SPM adds to income: implicit rent subsidies to those in government subsidized housing who pay below-market rents, lunch subsidies received by school children, transfers in federal nutrition programs for pregnant women and mothers of young children, and energy assistance. We recognize that liquidity issues can be raised with these estimates as well. Finally, we also, like the SIPM does for income, deduct from our expenditures work-related expenses and child care, child support paid, and capped medical out-of-pocket expenses, though all necessarily computed with CE data instead of the CPS. These “adjustments” are an important feature of the SPM poverty measure. With all these methods, we intend for our Current Resources SEPM and the SIPM to differ as much as possible only from the use of expenditures instead of income….”























