Lack of health insurance and type of coverage (Released 6/2010) Lack of health insurance and type of coverage Figure 1.1. Percentage of persons of all ages without health insurance coverage at the time of interview: United States, 1997-2009

Abstract 1 The quality of survey estimates depends on coverage of the target population, response rates, and measurement errors. Landline telephone surveys exclude households that do not have landline telephones including wireless-only households. Among children under 18 years of age, the prevalence of living in wireless-only households increased from 3.7 % in 2003 (January-June) to 19 % in 2008 (July-December) according to the National Health Interview Survey (NHIS). In addition, households with mixed telephone service where members primarily use wireless telephones for most calls (wireless-mostly) may not answer their landline telephones which results in survey noncontact. In 2007, wireless-mostly and wireless-only households accounted for 15 % and 13 % of children under 18 years of age, respectively. In the U.S., the prevalence of the wireless-only and wireless-mostly population has been consistently increasing and may affect the validity of estimates from telephone surveys such as the National Immunization Survey (NIS). Telephone status and interview data for children under 18 years of age from the NHIS-Sample-Child file are analyzed to compare alternative methods to adjust sampling weights and evaluate potential bias in weighted estimates. We used interview data to compare characteristics of children and estimates of selected outcome measures that are associated with health conditions and vaccinations. The purpose of this paper is to evaluate potential bias in RDD survey estimates after adjusting for noncoverage of households that do not have access to landline telephone.

Lack of health insurance and type of coverage (Released 6/2007) Lack of health insurance coverage and type of coverage Figure 1.1. Percentage of persons of all ages without health insurance coverage at the time of interview: United States, 1997–2006

Lack of health insurance and type of coverage (Released 9/2007) Lack of health insurance and type of coverage Figure 1.1. Percentage of persons of all ages without health insurance coverage at the time of interview: United States, 1997–March 2007

Lack of health insurance and type of coverage (Released 12/2009) Lack of health insurance and type of coverage Figure 1.1. Percentage of persons of all ages without health insurance coverage at the time of interview: United States, 1997-June 2009

Lack of health insurance and type of coverage (Released 3/2008) Lack of health insurance and type of coverage Figure 1.1. Percentage of persons of all ages without health insurance coverage at the time of interview: United States, 1997–September 2007

Lack of health insurance and type of coverage (Released 12/2007) Lack of health insurance and type of coverage Figure 1.1. Percentage of persons of all ages without health insurance coverage at the time of interview: United States, 1997–June 2007

Lack of health insurance and type of coverage (Released 6/2008) Lack of health insurance and type of coverage Figure 1.1. Percentage of persons of all ages without health insurance coverage at the time of interview: United States, 1997–2007

Lack of health insurance and type of coverage (Released 9/2008) Lack of health insurance and type of coverage Figure 1.1. Percentage of persons of all ages without health insurance coverage at the time of interview: United States, 1997–March 2008

Lack of health insurance and type of coverage (Released 12/2008) Lack of health insurance and type of coverage Figure 1.1. Percentage of persons of all ages without health insurance coverage at the time of interview: United States, 1997–June 2008