EXAMPLE 1 Did we miss anyone?

Most opinion polls can’t afford even to attempt full coverage of the population of all adult residents of the United States. The interviews are done by telephone, thus missing the 2% of households without phones. Only households are contacted, so students in dormitories, prison inmates, and most members of the armed forces are left out. So are the homeless and people staying in shelters. Many polls interview only in English, which leaves some immigrant households out of their samples.