DOT HS 809 788

Young Adult Over-Sample

The survey design specified an over-sample of 16-39 year olds in the achieved sample in order to permit more detailed analysis of this subset of the population. A random sample of all persons age 16 and over in an RDD sample of 6,000 households yields too few individuals in this range to allow very close examination. Therefore, to increase the sub-sample sizes of the 16-39 year olds, within a projectable national sample, an independent national sample was conducted of that population. The allocation of sample by region for the young adult over-sample was proportional to the regional distribution of that population. The household selection procedure through RDD was the same for the over-sample as for the national cross-sectional sample.

The screening criteria for the over-sample were different from the simple cross-section in that households were screened for persons age 16 to 39. This systematic screening of a national probability sample of households for a subset of the total household population should yield a random sample of that population. As in the case of the simple cross-sectional sample, if there was only one eligible respondent in the household then he or she was selected. If there was more than one eligible respondent, then the "most recent/next birthday" method of selection was used. The over-sample screener script is presented in Figure 2.

FIGURE 2
Within Household Selection Procedure:
Young Adult Over-Sample

TIME START: _____________ TIME END: _____________
DATE: _____________ BATCH #:____________ CATI RESP. #: ______________
SAMPLE POINT #: ___ ___ ___ GENDER OF RESP.: MALE [ ] FEMALE [ ]
RESP PHONE NUMBER: ___________________________________________________
RESP POSITION IN HOUSEHOLD: ________________________________________________
INTERVIEWER NAME: __________________________________________________________
THIS INTERVIEW IS A: COMPLETE [ ] CALLBACK FOR COMPLETION [ ]
TERMINATE AT Q_____ [ ]
INTRODUCTION TO BE ADMINISTERED TO ANY ADULT HOUSEHOLD MEMBER:
Hello, I'm calling for the U.S. Department of Transportation. We are conducting a study of Americans' driving habits and their attitudes about current driving laws. The interview is completely confidential.
D1. Is there anyone age 16 to 39 years old living in your household?

Yes [ASK QD2].................1
No [SCREEN-OUT D1 AGE].........2

D2. Could I speak to the person in your household, age 16 to 39, who has had the most recent/next birthday?
Respondent is that person [CONTINUE WITH CATI AND ENTER Q1 AS D2]...............1
Other respondent came to phone [ CONTINUE WITH CATI AND ENTER Q1 AS D2]......2 Respondent is not available.....................................................................................3
[ARRANGE CALLBACK AND RECORD IT, ALONG WITH THE RESPONDENT'S FIRST NAME OR HH POSITION, ON THE SAMPLE SHEET. ATTACH THIS SHEET TO SAMPLE AFTER FILLING OUT APPLICABLE RESPONDENT INFO AT THE TOP. WHEN THE NEXT INTERVIEWER REACHES THIS PERSON, THEY WILL ENTER Q1 AS D2]

Table 2 presents the national population estimates and projected sample distribution by age and sex for the total sample of 6,000 respondents in each survey, including the cross-sectional sample of 4,500 respondents and the over-sample of 1,500 persons aged 16-39.

	Population		Expected sample distribution
TABLE 2 Population and Expected Sample Distribution
	Total Population	%	Cross-Sectional Sample	Young Adult Sample	Total
Total (16+)	219,748,014	100.0%	4,500	1,500	6,000
Males (16+)	106,013,964	48.2%	2,171	752	2,923
16-20	10510182	4.8%	215	168	383
21-29	16696110	7.6%	342	267	609
30-39	19762473	9.0%	405	317	722
40-64	44115613	20.1%	903		903
65+	14929586	6.8%	306		306
Females (16+)	113,734,050	51.8%	2,329	748	3,077
16-20	9948226	4.5%	204	159	363
21-29	16501623	7.5%	338	264	602
30-39	20237015	9.2%	414	325	739
40-64	46342381	21.1%	949		949
65+	20704805	9.4%	424		424
Source:National Population Projections: 2001 to 2005, U.S. Bureau of the Census, Population Division, Populations Projections Branch, www.census.gov/population/www/projections/st_yr01to05.html, (release date, November 2, 2002).