Cell Phone Only Household

The widespread availability of cell phone service and the relatively low cost of such service means that some people are now indifferent as to whether they make a call on a landline or a mobile telephone. In fact, many people have substituted one or more wireless cell phones for their traditional household wired telephones (also called “residential landline telephones”). These cell phone only households pose a problem for most major survey research organizations in the United States because cell phone numbers are not typically included when conducting random-digit dial (RDD) telephone surveys in the United States.

The Telephone Consumer Protection Act of 1991 prohibits the use of autodialers in the United States when calling cell phones; therefore, the inclusion of such telephone numbers would be very expensive for most survey call centers because of the requirement to have interviewers dial the cell phone numbers manually. In addition, nonresponse rates may be high because most cell phone owners do not expect to receive survey calls on their cell phones, and some cell phone owners must pay to receive calls.

The inability to reach cell phone only households has potential implications for coverage bias in random-digit dialed telephone surveys. Coverage bias may exist if cell phone only households are not included in survey sampling frames and if persons [Page 83]living in cell phone only households differ on the survey variables of interest from persons living in households with landline telephones.

The National Health Interview Survey (NHIS) provides the most up-to-date estimates regularly available from the U.S. federal government concerning the prevalence and characteristics of cell phone only households. This cross-sectional, in-person, household survey of the U.S. civilian noninstitutionalized population, conducted annually by the National Center for Health Statistics of the Centers for Disease Control and Prevention, is designed to collect information on health status, health-related behaviors, and health care utilization. However, the survey also includes information about household telephones and whether anyone in the household has a working cell phone. Approximately 40,000 household interviews are completed each year.

NHIS data permit an analysis of trends in the prevalence of cell phone only households in the United States since 2003. The percentage of cell phone only households doubled from 2003 to 2005, and as of 2006, approximately 11% of U.S. households were cell phone only. The rate of growth in the size of this population has not slowed, increasing at a compound growth rate of more than 20% every 6 months. Cell phone only households now compose the vast majority of non-landline households. More than 80% of non-landline households have cell phone service in the household, and this proportion also continues to increase; the proportion was 62% during the first 6 months of 2003. This largely reflects the fact that the percentage of households without any telephone service has remained unchanged, whereas the percentage of cell phone only households has increased.

Since the NHIS began collecting data on cell phone only households and the persons who live in such households, the prevalence of cell phone only adults has been greatest for adults 18–24 years of age, adults renting their homes, and adults going to school. Men are more likely than women to be living in cell phone only households. Hispanic adults are slightly more likely to be living in cell phone only households than are non-Hispanic white adults or non-Hispanic black adults. Adults living in the Midwest, South, or West are more likely to be living in cell phone only households than are adults living in the Northeast. Adults living in urban households are more likely than adults living in rural households to be in cell phone only households.

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