The national statistics from these surveys are not identical because they collect income data differently. The CPS is the Census Bureau’s longest-running survey. Conducted monthly, it serves as the nation’s primary source of statistics on labor force characteristics. Supplemental surveys are added in most months.
Second, interviewers administer the CPS ASEC survey in person or over the phone, while people primarily respond to the ACS online or by mail . Interviewers follow up with households that do not respond to the ACS online or by mail. The reference periods for the two surveys are different.
These problems are: The conventional Census income figures are incomplete and omit many types of cash and non-cash income. The conventional Census figures do not take into account the equalizing effects of taxation.
To measure income distribution, the Census Bureau first ranks households from highest to lowest incomes. It then divides American society into five groups, called quintiles, and determines the share of total income received by each quintile.
According to conventional Census measurement methods, the top half of society received $4.1 trillion, or 81 percent of total income, in 1997. The bottom half of society, by contrast, received $973 billion, or 19 percent of the total.
Political debate on income in the United States often has been characterized as competition between two schools of economic thought: one that focuses on the long-term increase in general prosperity and one that focuses on the equalization of existing incomes. Proponents of the first approach have much to hearten them; the long-term increase in economic well-being in the United States has been enormous. Today, the standard of living for the average American is nearly seven times higher than it was 100 years ago, after adjusting for inflation. 2 The large gains in prosperity have affected all Americans, including low-income groups. At present, workers earning the minimum wage comprise the lowest-paid 2 percent of all employees. Yet today's minimum wage worker earns more, in real terms, in a single day than a low-skilled worker earned in an entire six-day workweek at the turn of the century. In other words, today's minimum wage worker earns more in eight hours than a low-skilled worker earned in 70 or more hours a century ago. 3
The top quintile has 65 percent more persons than does the bottom quintile. With conventional Census figures, the bottom "quintile" is hollow, representing far less than one-fifth of society; by contrast, the top "quintile" is overpopulated, containing far more than one-fifth of persons, workers, and work effort.
When decisionmakers, journalists, and the public view the government's official income distribution figures, there is a common and implicit assumption that the quintiles contain equal shares of the population. After all, the notion that we should measure "inequality" by comparing the aggregate incomes of groups that are, themselves, unequal in size is at best confusing. However, as noted, the official Census income "quintiles" do not contain equal shares of the population, and this fact skews the Census Bureau's measure of income distribution.
By contrast, individuals are not treated equally in the current Census methods; in general, individuals in married couple families are underrepresented by the Census data and treated as less significant than single persons or people in single-parent families.