Wireless Substitution: Early Release of Estimates From the National Health Interview Survey, January - June 2008

by Stephen J. Blumberg, Ph.D., and Julian V. Luke, Division of Health Interview Statistics, National Center for Health Statistics

Table 1

Table 1a. Percent distribution of household telephone status, by date of interview, for households: United States, January 2005-June 2008

		Household telephone status
Date of interview		Landline households with a wireless telephone	Landline households without a wireless telephone	Landline households with unknown wireless telephone status	Nonlandline households with unknown wireless telephone status	Wireless-only households	Phoneless households	Total
	Number of households (unweighted)	Percent of households
January-June 2005	18,301	42.4	34.4	13.2	0.8	7.3	1.9	100.0
July-December 2005	20,088	42.6	32.4	13.8	0.8	8.4	1.9	100.0
January-June 2006	16,009	45.6	30.9	10.3	0.7	10.5	2.0	100.0
July-December 2006	13,056	44.3	29.6	10.2	0.8	12.8	2.2	100.0
January-June 2007 1	15,996	58.9	23.8	1.7	0.1	13.6	1.9	100.0
July-December 2007 1	13,083	58.8	21.8	1.3	0.1	15.8	2.2	100.0
January-June 2008	16,070	58.5	20.6	0.9	0.0	17.5	2.5	100.0
95% confidence interval2		57.11 - 59.86	19.35 - 21.91	0.71 - 1.16	0.02 - 0.09	16.58 - 18.40	2.11 - 2.91

See footnotes at end of table 1c.

Table 1b. Percent distribution of household telephone status, by date of interview, for adults: United States, January 2005-June 2008

		Household telephone status
Date of interview		Landline households with a wireless telephone	Landline households without a wireless telephone	Landline households with unknown wireless telephone status	Nonlandline households with unknown wireless telephone status	Wireless-only households	Phoneless households	Total
	Number of adults (unweighted)	Percent of adults
January-June 2005	34,047	46.1	31.5	13.5	0.7	6.7	1.6	100.0
July-December 2005	37,622	46.4	29.7	13.9	0.7	7.7	1.7	100.0
January-June 2006	29,842	49.5	28.2	10.4	0.6	9.6	1.8	100.0
July-December 2006	24,473	48.1	27.3	10.5	0.7	11.8	1.7	100.0
January-June 2007 1	29,982	63.3	20.8	1.7	0.1	12.6	1.6	100.0
July-December 2007 1	24,514	63.2	19.1	1.2	0.1	14.5	1.9	100.0
January-June 2008	30,150	63.0	17.9	0.8	0.0	16.1	2.1	100.0
95% confidence interval2		61.64 - 64.36	16.69 - 19.22	0.62 - 1.03	0.02 - 0.09	15.29 - 17.01	1.80 - 2.43

See footnotes at end of table 1c.

Table 1c. Percent distribution of household telephone status, by date of interview, for children: United States, January 2005-June 2008

		Household telephone status
Date of interview		Landline households with a wireless telephone	Landline households without a wireless telephone	Landline households with unknown wireless telephone status	Nonlandline households with unknown wireless telephone status	Wireless-only households	Phoneless households	Total
	Number of children (unweighted)	Percent of children
January-June 2005	12,903	49.3	27.0	15.8	0.7	5.8	1.5	100.0
July-December 2005	13,883	50.5	23.9	15.2	0.9	7.6	1.8	100.0
January-June 2006	11,670	53.4	23.8	11.5	0.9	8.6	1.9	100.0
July-December 2006	9,165	51.9	21.5	11.9	0.9	11.6	2.3	100.0
January-June 2007 1	11,532	68.3	16.4	1.6	0.0	11.9	1.7	100.0
July-December 2007 1	9,122	68.5	13.8	1.1	0.0	14.4	2.1	100.0
January-June 2008	11,238	67.3	12.6	0.6	0.0	17.0	2.5	100.0
95% confidence interval2		65.28 - 69.23	11.13 - 14.13	0.40 - 0.93	0.01 - 0.10	15.76 - 18.35	1.97 - 3.18

0.0. Quantity more than zero but less than 0.05.

¹ Questionnaire changes that occurred in 2007 should be considered when evaluating recent trends in household telephone status. See text for more information about these changes.

² Confidence intervals refer to the time period January-June 2008.

DATA SOURCE: National Health Interview Survey, January 2005-June 2008. Data are based on household interviews of a sample of the civilian noninstitutionalized population.

Table 2

Table 2a. Percentage of adults living in wireless-only households, by race/ethnicity and by calendar half-years: United States, January 2005-June 2008

	Calendar half-year
Race/ethnicity	Jan-Jun 2005	Jul-Dec 2005	Jan-Jun 2006	Jul-Dec 2006	Jan-Jun 2007 1	Jul-Dec 2007 1	Jan-Jun 2008	95% confidence interval2
	Percent
Hispanic or Latino, any race(s)	8.5	11.2	11.2	15.3	18.0	19.3	21.6	(19.72 - 23.61)
Non-Hispanic white, single race	6.5	6.9	9.0	10.8	11.3	12.9	14.6	(13.55 - 15.69)
Non-Hispanic black, single race	6.6	8.5	10.5	12.8	14.3	18.3	18.5	(16.93 - 20.09)
Non-Hispanic Asian, single race	5.3	6.7	10.2	11.8	10.6	12.1	16.5	(13.89 - 19.49)
Non-Hispanic other, single race	*11.1	*8.0	9.8	17.2	22.8	17.5	12.8	(8.07 - 19.85)
Non-Hispanic multiple race	8.1	11.5	15.4	14.6	17.3	22.8	22.3	(16.82 - 28.98)

See footnotes at end of table 2k.

Table 2b. Percentage of adults living in wireless-only households, by age and by calendar half-years: United States, January 2005-June 2008

	Calendar half-year
Age	Jan-Jun 2005	Jul-Dec 2005	Jan-Jun 2006	Jul-Dec 2006	Jan-Jun 2007 1	Jul-Dec 2007 1	Jan-Jun 2008	95% confidence interval2
	Percent
18-24 years	16.6	17.5	22.6	25.2	27.9	30.6	31.4	(28.50 - 34.36)
25-29 years	16.5	19.8	22.3	29.1	30.6	34.5	35.7	(33.34 - 38.21)
30-44 years	6.5	7.8	9.4	12.4	12.6	15.5	19.1	(17.93 - 20.34)
45-64 years	3.2	3.7	5.3	6.1	7.1	8.0	9.2	(8.45 - 10.04)
65 years and over	0.9	1.2	1.3	1.9	2.0	2.2	2.8	(2.29 - 3.47)

See footnotes at end of table 2k.

Table 2c. Percentage of adults living in wireless-only households, by sex and by calendar half-years: United States, January 2005-June 2008

	Calendar half-year
Age	Jan-Jun 2005	Jul-Dec 2005	Jan-Jun 2006	Jul-Dec 2006	Jan-Jun 2007 1	Jul-Dec 2007 1	Jan-Jun 2008	95% confidence interval2
	Percent
Male	7.5	8.6	10.7	13.1	13.8	15.9	18.0	(16.94-19.01)
Female	6.0	6.9	8.5	10.5	11.5	13.2	14.4	(13.62-15.28)

See footnotes at end of table 2k.

Table 2d. Percentage of adults living in wireless-only households, by education and by calendar half-years: United States, January 2005-June 2008

	Calendar half-year
Education	Jan-Jun 2005	Jul-Dec 2005	Jan-Jun 2006	Jul-Dec 2006	Jan-Jun 2007 1	Jul-Dec 2007 1	Jan-Jun 2008	95% confidence interval2
	Percent
Some high school or less	6.7	8.0	8.3	12.9	14.6	15.4	16.1	(14.63-17.78)
High school graduate or GED3	6.9	7.6	9.6	10.6	11.8	13.4	15.2	(14.07-16.34)
Some post-high school, no degree	8.2	9.4	11.9	14.4	14.7	17.0	19.0	(17.46-20.58)
4-year college degree or higher	5.5	6.3	8.5	10.1	10.8	12.7	14.3	(12.97-15.71)

See footnotes at end of table 2k.

Table 2e. Percentage of adults living in wireless-only households, by employment status last week and by calendar half-years: United States, January 2005-June 2008

	Calendar half-year
Employment Status Last Week	Jan-Jun 2005	Jul-Dec 2005	Jan-Jun 2006	Jul-Dec 2006	Jan-Jun 2007 1	Jul-Dec 2007 1	Jan-Jun 2008	95% confidence interval2
	Percent
Working at a job or business	8.0	9.2	11.6	13.9	15.0	16.6	19.0	(18.02-20.07)
Keeping house	5.1	6.1	7.1	8.6	9.5	12.8	12.6	(10.97-14.46)
Going to school	10.8	15.5	17.3	20.4	21.3	28.9	21.5	(16.41-27.74)
Something else (incl. unemployed)	3.6	3.7	4.2	6.2	6.4	7.6	8.9	(7.99-9.82)

See footnotes at end of table 2k.

Table 2f. Percentage of adults living in wireless-only households, by household structure and by calendar half-years: United States, January 2005-June 2008

	Calendar half-year
Household Structure	Jan-Jun 2005	Jul-Dec 2005	Jan-Jun 2006	Jul-Dec 2006	Jan-Jun 2007 1	Jul-Dec 2007 1	Jan-Jun 2008	95% confidence interval2
	Percent
Adult living alone	11.2	12.3	16.2	18.2	20.3	22.9	24.6	(22.72-26.61)
Unrelated adults, no children	36.0	33.6	44.2	54.0	55.3	56.9	63.1	(51.28-73.47)
Related adults, no children	5.3	5.9	7.1	8.5	9.8	11.0	12.5	(11.49-13.49)
Adult(s) with children	5.4	7.0	8.6	10.5	11.3	13.0	15.1	(14.07-16.25)

See footnotes at end of table 2k.

Table 2g. Percentage of adults living in wireless-only households, by household poverty status and by calendar half-years: United States, January 2005-June 2008

	Calendar half-year
Household poverty status4	Jan-Jun 2005	Jul-Dec 2005	Jan-Jun 2006	Jul-Dec 2006	Jan-Jun 2007 1	Jul-Dec 2007 1	Jan-Jun 2008	95% confidence interval2
	Percent
Poor	11.8	14.2	15.8	22.4	21.6	27.4	26.0	(23.04-29.15)
Near poor	10.8	12.7	14.4	15.7	18.5	20.8	22.6	(20.44-24.95)
Not poor	6.2	7.0	9.4	11.3	10.6	11.9	14.2	(13.24-15.12)

See footnotes at end of table 2k.

Table 2h. Percentage of adults living in wireless-only households, by geographic region and by calendar half-years: United States, January 2005-June 2008

	Calendar half-year
Geographic Region5	Jan-Jun 2005	Jul-Dec 2005	Jan-Jun 2006	Jul-Dec 2006	Jan-Jun 2007 1	Jul-Dec 2007 1	Jan-Jun 2008	95% confidence interval2
	Percent
Northeast	4.1	4.7	7.2	8.6	8.8	10.0	9.8	(8.47-11.33)
Midwest	7.2	8.8	10.2	11.4	14.0	15.3	17.8	(15.83-19.86)
South	7.6	9.6	11.4	14.0	14.9	17.1	19.6	(18.07-21.14)
West	7.0	6.2	7.8	11.0	10.9	12.9	13.7	(12.28-15.36)

See footnotes at end of table 2k.

Table 2i. Percentage of adults living in wireless-only households, by metropolitan statistical area status and by calendar half-years: United States, January 2005-June 2008

	Calendar half-year
Metropolitan Statistical Area Status	Jan-Jun 2005	Jul-Dec 2005	Jan-Jun 2006	Jul-Dec 2006	Jan-Jun 2007 1	Jul-Dec 2007 1	Jan-Jun 2008	95% confidence interval2
	Percent
Metropolitan	7.7	8.7	10.3	12.7	13.7	15.5	17.5	(16.53-18.53)
Not metropolitan	4.1	5.1	7.0	8.0	8.4	10.0	10.9	(9.52-12.42)

See footnotes at end of table 2k.

Table 2j. Percentage of adults living in wireless-only households, by home ownership status and by calendar half-years: United States, January 2005-June 2008

	Calendar half-year
Home Ownership Status6	Jan-Jun 2005	Jul-Dec 2005	Jan-Jun 2006	Jul-Dec 2006	Jan-Jun 2007 1	Jul-Dec 2007 1	Jan-Jun 2008	95% confidence interval2
	Percent
Owned or being bought	3.1	3.8	5.1	5.8	6.7	7.3	9.0	(8.32-9.77)
Renting	16.7	19.3	22.5	26.4	28.2	30.9	33.6	(31.57-35.70)
Other arrangement	10.7	8.4	10.7	*20.3	22.5	23.2	23.4	(17.89-29.87)

See footnotes at end of table 2k.

Table 2k. Number of adults living in wireless-only households, by calendar half-years: National Health Interview Survey, January 2005-June 2008

	Calendar half-year
	Jan-Jun 2005	Jul-Dec 2005	Jan-Jun 2006	Jul-Dec 2006	Jan-Jun 2007 1	Jul-Dec 2007 1	Jan-Jun 2008	95% confidence interval2
	Number
Number of wireless-only adults in survey sample (unweighted)	2,263	2,918	2,804	2,878	3,819	3,558	4,939

* Estimate has a relative standard error greater than 30% and does not meet NCHS standards for reliability.

¹ Questionnaire changes that occurred in 2007 should be considered when evaluating recent trends in household telephone status. See text for more information about these changes.

²Confidence intervals refer to the time period January-June 2008.

³ GED is General Educational Development high school equivalency diploma.

⁴ Poverty status is based on household income and household size using the U.S. Census Bureau's poverty thresholds. "Poor" persons are defined as those below the poverty threshold. "Near poor" persons have incomes of 100% to less than 200% of the poverty threshold. "Not poor" persons have incomes of 200% of the poverty threshold or greater. Early Release estimates stratified by poverty are based only on the reported income and may differ from similar estimates produced later that are based on both reported and imputed income. NCHS imputes income when income is unknown, but the imputed income file is not available until a few months after the annual release of NHIS microdata. For households with multiple families, household income and household size were calculated as the sum of the multiple measures of family income and family size.

⁵ In the geographic classification of the U.S. population, states are grouped into the following four regions used by the U.S. Census Bureau. Northeast includes Maine, Vermont, New Hampshire, Massachusetts, Connecticut, Rhode Island, New York, New Jersey, and Pennsylvania. Midwest includes Ohio, Illinois, Indiana, Michigan, Wisconsin, Minnesota, Iowa, Missouri, North Dakota, South Dakota, Kansas, and Nebraska. South includes Delaware, Maryland, District of Columbia, West Virginia, Virginia, Kentucky, Tennessee, North Carolina, South Carolina, Georgia, Florida, Alabama, Mississippi, Louisiana, Oklahoma, Arkansas, and Texas. West includes Washington, Oregon, California, Nevada, New Mexico, Arizona, Idaho, Utah, Colorado, Montana, Wyoming, Alaska, and Hawaii.

⁶ For households with multiple families, home ownership status was determined by considering the reported home ownership status for each family. If any family reported owning the home, than the household level variable was classified as "owned or being bought" for all persons living in the household. If one family reported renting the home and another family reported "other arrangements," then the household level variable was classified as "other arrangement" for all persons living in the household.

Table 3

Table 3a. Percentage of adults living in landline households with wireless telephones, by proportions of calls received on wireless telephones, by total and by calendar half-years: United States, July 2007-June 2008

	July-December 2007		January-June 2008
	Receive some or very few calls on wireless phones1	Receive all or nearly all calls on wireless phones1	Receive some or very few calls on wireless phones	Receive all or nearly all calls on wireless phones	95% confidence interval2
	Percent
Total	48.6	14.0	48.0	14.4	(13.59-15.32)

See footnotes at end of table 3l.

Table 3b. Percentage of adults living in landline households with wireless telephones, by proportions of calls received on wireless telephones, by race/ethnicity and by calendar half-years: United States, July 2007-June 2008

	July-December 2007		January-June 2008
Race/Ethnicity	Receive some or very few calls on wireless phones1	Receive all or nearly all calls on wireless phones1	Receive some or very few calls on wireless phones	Receive all or nearly all calls on wireless phones	95% confidence interval2
	Percent
Hispanic or Latino, any race(s)	41.1	14.5	38.9	16.0	(14.13-18.16)
Non-Hispanic white, single race	51.7	13.2	50.6	14.2	(13.23-15.18)
Non-Hispanic black, single race	39.7	15.1	43.5	13.3	(11.62-15.16)
Non-Hispanic Asian, single race	50.5	20.3	49.7	16.4	(13.84-19.39)
Non-Hispanic other single race	40.7	*8.6	37.1	*10.1	(4.94-19.40)
Non-Hispanic multiple race	37.8	19.7	41.1	17.7	(11.55-26.12)

See footnotes at end of table 3l.

Table 3c. Percentage of adults living in landline households with wireless telephones, by proportions of calls received on wireless telephones, by age and by calendar half-years: United States, July 2007-June 2008

	July-December 2007		January-June 2008
Age	Receive some or very few calls on wireless phones1	Receive all or nearly all calls on wireless phones1	Receive some or very few calls on wireless phones	Receive all or nearly all calls on wireless phones	95% confidence interval2
	Percent
18-24 years	35.8	18.2	35.6	19.2	(16.30-22.36)
25-29 years	31.6	19.7	32.2	17.3	(15.58-19.13)
30-44 years	49.5	17.3	46.8	18.2	(16.94-19.47)
45-64 years	56.9	13.0	56.4	13.8	(12.76-14.80)
65 years or more	49.6	3.9	50.9	4.4	(3.72-5.24)

See footnotes at end of table 3l.

Table 3d. Percentage of adults living in landline households with wireless telephones, by proportions of calls received on wireless telephones, by sex and by calendar half-years: United States, July 2007-June 2008

	July-December 2007		January-June 2008
Sex	Receive some or very few calls on wireless phones1	Receive all or nearly all calls on wireless phones1	Receive some or very few calls on wireless phones	Receive all or nearly all calls on wireless phones	95% confidence interval2
	Percent
Male	48.1	14.3	46.8	14.9	(13.92-15.85)
Female	49.2	13.6	49.1	14.0	(13.19-14.91)

See footnotes at end of table 3l.

Table 3e. Percentage of adults living in landline households with wireless telephones, by proportions of calls received on wireless telephones, by education and by calendar half-years: United States, July 2007-June 2008

	July-December 2007		January-June 2008
Education	Receive some or very few calls on wireless phones1	Receive all or nearly all calls on wireless phones1	Receive some or very few calls on wireless phones	Receive all or nearly all calls on wireless phones	95% confidence interval2
	Percent
Some high school or less	37.7	8.7	39.3	10.0	(8.63-11.61)
High school graduate or GED3	46.1	12.7	46.4	12.5	(11.45-13.63)
Some post-high school, no degree	49.6	16.6	48.2	17.0	(15.43-18.81)
4-year college degree or higher	58.3	16.2	56.0	17.1	(15.87-18.36)

See footnotes at end of table 3l.

Table 3f. Percentage of adults living in landline households with wireless telephones, by proportions of calls received on wireless telephones, by employment status last week and by calendar half-years: United States, July 2007-June 2008

	July-December 2007		January-June 2008
Employment Status Last Week	Receive some or very few calls on wireless phones1	Receive all or nearly all calls on wireless phones1	Receive some or very few calls on wireless phones	Receive all or nearly all calls on wireless phones	95% confidence interval2
	Percent
Working at a job or business	49.9	16.8	48.7	17.3	(16.40-18.25)
Keeping house	52.9	10.4	50.2	11.9	(10.33-13.72)
Going to school	37.2	20.4	39.9	25.2	(16.24-36.92)
Something else (incl. unemployed)	46.4	6.7	46.7	6.6	(5.88-7.45)

See footnotes at end of table 3l.

Table 3g. Percentage of adults living in landline households with wireless telephones, by proportions of calls received on wireless telephones, by household structure and by calendar half-years: United States, July 2007-June 2008

	July-December 2007		January-June 2008
Household Structure	Receive some or very few calls on wireless phones1	Receive all or nearly all calls on wireless phones1	Receive some or very few calls on wireless phones	Receive all or nearly all calls on wireless phones	95% confidence interval2
	Percent
Adult living alone	27.9	10.7	27.8	10.1	(8.61-11.84)
Unrelated adults, no children	13.0	20.1	10.0	*15.4	(7.70-28.39)
Related adults, no children	53.6	12.1	53.1	12.8	(11.81-13.91)
Adult(s) with children	53.1	17.2	51.6	18.1	(16.81-19.41)

See footnotes at end of table 3l.

Table 3h. Percentage of adults living in landline households with wireless telephones, by proportions of calls received on wireless telephones, by household poverty status and by calendar half-years: United States, July 2007-June 2008

	July-December 2007		January-June 2008
Household Poverty Status4	Receive some or very few calls on wireless phones1	Receive all or nearly all calls on wireless phones1	Receive some or very few calls on wireless phones	Receive all or nearly all calls on wireless phones	95% confidence interval2
	Percent
Poor	24.2	8.6	22.4	10.8	(7.33-15.64)
Near poor	36.0	11.4	39.3	10.3	(8.41-12.59)
Not poor	57.0	15.9	54.8	17.1	(16.18-18.15)

See footnotes at end of table 3l.

Table 3i. Percentage of adults living in landline households with wireless telephones, by proportions of calls received on wireless telephones, by geographic region and by calendar half-years: United States, July 2007-June 2008

	July-December 2007		January-June 2008
Geographic Region5	Receive some or very few calls on wireless phones1	Receive all or nearly all calls on wireless phones1	Receive some or very few calls on wireless phones	Receive all or nearly all calls on wireless phones	95% confidence interval2
	Percent
Northeast	52.4	11.7	53.0	13.8	(11.98-15.89)
Midwest	48.0	13.3	47.6	12.6	(10.70-14.85)
South	46.4	14.3	46.6	14.6	(13.39-16.00)
West	49.9	15.9	46.7	16.4	(14.62-18.32)

See footnotes at end of table 3l.

Table 3j. Percentage of adults living in landline households with wireless telephones, by proportions of calls received on wireless telephones, by metropolitan statistical area status and by calendar half-years: United States, July 2007-June 2008

	July-December 2007		January-June 2008
Metropolitan Statistical Area Status	Receive some or very few calls on wireless phones1	Receive all or nearly all calls on wireless phones1	Receive some or very few calls on wireless phones	Receive all or nearly all calls on wireless phones	95% confidence interval2
	Percent
Metropolitan	48.1	14.7	46.5	15.0	(14.06-16.06)
Not metropolitan	51.0	10.9	53.5	12.1	(10.67-13.80)

See footnotes at end of table 3l.

Table 3k. Percentage of adults living in landline households with wireless telephones, by proportions of calls received on wireless telephones, by home ownership status and by calendar half-years: United States, July 2007-June 2008

	July-December 2007		January-June 2008
Home Ownership Status6	Receive some or very few calls on wireless phones1	Receive all or nearly all calls on wireless phones1	Receive some or very few calls on wireless phones	Receive all or nearly all calls on wireless phones	95% confidence interval2
	Percent
Owned or being bought	57.8	14.0	57.2	14.7	(13.83-15.69)
Renting	29.0	13.8	26.9	13.9	(12.16-15.86)
Other arrangement	33.9	14.1	30.8	14.8	(10.50-20.46)

See footnotes at end of table 3l.

Table 3l. Number of adults living in wireless-only households, by proportions of calls received on wireless telephones, by home ownership status and by calendar half-years: United States, July 2007-June 2008

	July-December 2007		January-June 2008
	Receive some or very few calls on wireless phones1	Receive all or nearly all calls on wireless phones1	Receive some or very few calls on wireless phones	Receive all or nearly all calls on wireless phones	95% confidence interval2
	Number
Number of adults in survey sample who live in landline households with wireless telephones (unweighted)	11,779	3,435	14,187	4,302

* Estimate has a relative standard error greater than 30% and does not meet NCHS standards for reliability.

¹ The percentage of adults living in landline households with wireless telephones (see Table 1) is equal to the sum of the percentage of adults in households that receive some or very few calls on wireless phones and the percentage of adults in households that receive all or nearly all calls on wireless phones.

² Confidence intervals refer to the estimate of the percentage of adults living in households that receive all or nearly all calls on wireless telephones, for the time period January-June 2008.

³ GED is General Educational Development high school equivalency diploma.

⁴ Poverty status is based on household income and household size using the U.S. Census Bureau's poverty thresholds. "Poor" persons are defined as those below the poverty threshold. "Near poor" persons have incomes of 100% to less than 200% of the poverty threshold. "Not poor" persons have incomes of 200% of the poverty threshold or greater. Early Release estimates stratified by poverty are based only on the reported income and may differ from similar estimates produced later that are based on both reported and imputed income. NCHS imputes income when income is unknown, but the imputed income file is not available until a few months after the annual release of NHIS microdata. For households with multiple families, household income and household size were calculated as the sum of the multiple measures of family income and family size.

⁵ In the geographic classification of the U.S. population, states are grouped into the following four regions used by the U.S. Census Bureau. Northeast includes Maine, Vermont, New Hampshire, Massachusetts, Connecticut, Rhode Island, New York, New Jersey, and Pennsylvania. Midwest includes Ohio, Illinois, Indiana, Michigan, Wisconsin, Minnesota, Iowa, Missouri, North Dakota, South Dakota, Kansas, and Nebraska. South includes Delaware, Maryland, District of Columbia, West Virginia, Virginia, Kentucky, Tennessee, North Carolina, South Carolina, Georgia, Florida, Alabama, Mississippi, Louisiana, Oklahoma, Arkansas, and Texas. West includes Washington, Oregon, California, Nevada, New Mexico, Arizona, Idaho, Utah, Colorado, Montana, Wyoming, Alaska, and Hawaii.

⁶ For households with multiple families, home ownership status was determined by considering the reported home ownership status for each family. If any family reported owning the home, than the household level variable was classified as "owned or being bought" for all persons living in the household. If one family reported renting the home and another family reported "other arrangements," then the household level variable was classified as "other arrangement" for all persons living in the household.

DATA SOURCE: National Health Interview Survey, July 2007-June 2008. Data are based on household interviews of a sample of the civilian noninstitutionalized population.

Table 4

Table 4a. Prevalence rates (and 95% confidence intervals) for selected measures of health-related behaviors for adults 18 years of age and over, by household telephone status: United States, January-June 2008

	Household telephone service
Health-related behaviors	Landline household1	Wireless-only household	Phoneless household
	Percent (95% confidence interval)
Five or more alcoholic drinks in 1 day at least once in past year2	17.2 (16.15-18.27)	37.7 (35.28-40.17)	20.9 (15.98-26.92)
Current smoker3	18.4 (17.31-19.48)	30.2 (27.89-32.56)	40.4 (33.97-47.26)
Engaged in regular leisure-time physical activity4	30.2 (28.89-31.60)	35.6 (33.09-38.18)	23.9 (19.05-29.48)

See footnotes at end of table 4e.

Table 4b. Prevalence rates (and 95% confidence intervals) for selected measures of health status for adults 18 years of age and over, by household telephone status: United States, January-June 2008

	Household telephone service
Health Status	Landline household1	Wireless-only household	Phoneless household
	Percent (95% confidence interval)
Health status described as excellent or very good5	60.5 (59.13-61.83)	66.0 (63.72-68.30)	46.6 (39.67-53.71)
Experienced serious psychological distress in past 30 days6	2.8 (2.40-3.23)	3.8 (2.92-4.97)	4.5 (2.49-8.09)
Obese (adults 20 years of age or older)7	27.4 (26.31-28.51)	25.6 (23.53-27.86)	25.0 (19.54-31.38)
Asthma episode in the past year8	3.3 (2.89-3.81)	4.5 (3.66-5.58)	4.8 (2.89-7.90)
Ever diagnosed with diabetes9	8.7 (8.10-9.39)	4.5 (3.55-5.67)	8.7 (6.07-12.21)

See footnotes at end of table 4e.

Table 4c. Prevalence rates (and 95% confidence intervals) for selected measures of health care service use for adults 18 years of age and over, by household telephone status: United States, January-June 2008

	Household telephone service
Health Care Service Use	Landline household1	Wireless-only household	Phoneless household
	Percent (95% confidence interval)
Received influenza vaccine during past year10	35.7 (34.47-36.90)	19.2 (17.48-21.08)	20.8 (16.30-26.19)
Ever been tested for HIV11	35.8 (34.40-37.13)	49.3 (46.71-51.95)	43.6 (37.24-50.26)

See footnotes at end of table 4e.

Table 4d. Prevalence rates (and 95% confidence intervals) for selected measures of health care access use for adults 18 years of age and over, by household telephone status: United States, January-June 2008

	Household telephone service
Health Care Access	Landline household1	Wireless-only household	Phoneless household
	Percent (95% confidence interval)
Has a usual place to go for medical care12	87.5 (86.48-88.37)	69.9 (67.49-72.15)	63.0 (55.19-70.20)
Failed to obtain needed medical care in past year due to financial barriers13	6.5 (5.99-7.15)	14.0 (12.48-15.68)	17.7 (13.32-23.11)
Currently uninsured14	13.6 (12.58-14.68)	28.3 (25.96-30.86)	36.3 (29.73-43.32)

See footnotes at end of table 4e.

Table 4e. Number of adults adults 18 years of age and over, by household telephone status: United States, January-June 2008

	Household telephone service
	Landline household1	Wireless-only household	Phoneless household
Number of adults in survey sample (unweighted)	9,792	2,479	323

* Estimate has a relative standard error greater than 30% and does not meet NCHS standards for reliability.

¹ In this analysis, landline households include households that also have wireless telephone service.

² A year is defined as the 12 months prior to the interview. The analyses excluded adults with unknown alcohol consumption (about 2% of respondents each year).

³ Current smokers were defined as those who smoked more than 100 cigarettes in their lifetime and now smoke every day or some days. The analyses excluded persons with unknown smoking status (about 1% of respondents each year).

⁴ Regular leisure-time physical activity is defined as engaging in light-moderate leisure-time physical activity for greater than or equal to 30 minutes at a frequency greater than or equal to five times per week or engaging in vigorous leisure-time physical activity for greater than or equal to 20 minutes at a frequency greater than or equal to three times per week. Persons who were known to have not met the frequency recommendations are classified as "not regular," regardless of duration. The analyses excluded persons with unknown physical activity participation (about 3% of respondents each year).

⁵ Health status data were obtained by asking respondents to assess their own health and that of family members living in the same household as excellent, very good, good, fair, or poor. The analyses excluded persons with unknown health status (about 0.5% of respondents each year).

⁶ Six psychological distress questions are included in the NHIS. These questions ask how often during the past 30 days a respondent experienced certain symptoms of psychological distress (feeling so sad that nothing could cheer you up, nervous, restless or fidgety, hopeless, worthless, that everything was an effort). The response codes of the six items for each person are summed to yield a scale with a 0-to-24 range. A value of 13 or more for this scale indicates that at least one symptom was experienced "most of the time" and is used here to define serious psychological distress.

⁷ Obesity is defined as a Body Mass Index (BMI) of 30 kg/m2 or more. The measure is based on self-reported height and weight. The analyses excluded people with unknown height or weight (about 4% of respondents each year).

⁸ Information on an episode of asthma or asthma attack during the past year is self-reported by adults aged 18 years and over. A year is defined as the 12 months prior to the interview. The analyses excluded people with unknown asthma episode status (about 0.3% of respondents each year).

⁹ Prevalence of diagnosed diabetes is based on self-report of ever having been diagnosed with diabetes by a doctor or other health professional. Persons reporting "borderline" diabetes status and women reporting diabetes only during pregnancy were not coded as having diabetes in the analyses. The analyses excluded persons with unknown diabetes status (about 0.1% of respondents each year).

¹⁰ Receipt of flu shots and receipt of nasal spray flu vaccinations were included in the calculation of flu vaccination estimates. Responses to the flu vaccination questions cannot be used to determine when the subject received the flu vaccination during the 12 months preceding the interview. In addition, estimates are subject to recall error, which will vary depending on when the question is asked because the receipt of a flu vaccination is seasonal. The analyses excluded those with unknown flu vaccination status (about 1% of respondents each year).

¹¹ Individuals who received HIV testing solely as a result of blood donation were considered as not having been tested for HIV. The analyses excluded those with unknown human immunodeficiency virus (HIV) test status (about 4% of respondents each year).

¹² The usual place to go for medical care does not include a hospital emergency room. The analyses excluded persons with an unknown usual place to go for medical care (about 0.6% of respondents each year).

¹³ A year is defined as the 12 months prior to the interview. The analyses excluded persons with unknown responses to the question on failure to obtain needed medical care due to cost (about 0.5% of respondents each year).

¹⁴ A person was defined as uninsured if he or she did not have any private health insurance, Medicare, Medicaid, State Children's Health Insurance Program (SCHIP), state-sponsored or other government-sponsored health plan, or military plan at the time of the interview. A person was also defined as uninsured if he or she had only Indian Health Service coverage or had only a private plan that paid for one type of service such as accidents or dental care. The data on health insurance status were edited using an automated system based on logic checks and keyword searches. The analyses excluded persons with unknown health insurance status (about 1% of respondents each year).

DATA SOURCE: National Health Interview Survey, January-June 2008. Data are based on household interviews of a sample of the civilian noninstitutionalized population.