I've seen those words in some writings but can't figure out the meaning.
What does that mean? Is it a common usage?
For your reference, some of the writings are as follows below.
Thus we see that, for a time, increasing age means increasing income, and therefore a probable boost 75 in income-tenth position. Although there are no extensive data in the matter, it can be confidently asserted that the higher income-tenths have a much greater representation of spending units headed by persons aged thirty-five to fifty-five than do the 80 lower-income-tenths. This is demonstrably the case among the richest 5 percent of the consumer units. The real question is: To what extent does distribution of income-tenths within a certain age group deviate from dis tribution of income-tenths 85 generally?
Studies which claim that the U.S. has a higher poverty rate than European nations use a distorted technique that creates higher income standard for assessing poverty in the United States than in other nations. Because of these biased methods, many Americans are deemed "poor" when, in fact, they have higher real incomes than persons identified as "non-poor" in Europe. By contrast, if a fair, uniform standard of comparison is used, the lowest income tenth of the U.S. population is found to have a real income that is roughly equal to, or higher than, most European nations. The median income in the U.S. is also higher than nearly all European nations.
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