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Omnibus Survey Household Survey Month Specific Information February 2003

Omnibus Survey
Household Survey
Month Specific Information
February 2003

This report presents the results of the February 2003 Omnibus Household Survey. Starting in December 2002, the Omnibus Household Surveys are now fielded on a bi-monthly basis.

Each bi-monthly survey will contain a set of core questions that are based on critical information needs within DOT. In addition, supplemental questions will be included that correspond to one of the U.S. Department of Transportation's (DOT) five strategic goals: safety, mobility, economic growth, human and natural environment, and security. Finally, specific questions posed by the various DOT modes will be included and will vary from month to month.

The February 2003 survey collected data from February 1, 2003 through February 13, 2003. Data were collected from households in the U.S. using a Random-Digit-Dialed telephone methodology. The final completed sample size is 1,015 cases, and the total number of variables in the public-use dataset is 209. The data were collected by M. Davis and Company (MDAC), under contract with the Bureau of Transportation Statistics (BTS).

Sample Telephone Number Selection

There were 8,200 telephone numbers for the February 2003 survey. A total of 5,113 of these numbers were identified as working residential numbers and were divided into 102 replicates. Each of the 59 fielding replicates released initially contained approximately 50 households. Two additional replicates were released during Fielding. Eight (8) unused replicates from February's sample were used to conduct a pretest. Each pretest replicate had approximately 50 households. Thirty-five (35) of the 102 February replicates were not utilized in the actual interviewing, resulting in 2,930 numbers being released for use by the telephone interviewers. For this survey, the total number of telephone numbers in the sampling frame, N, is 270,569,400. The total number of telephone numbers in the sample (numbers dialed) is 2,930.

Specific Weight Adjustment for Households with Multiple Telephone Numbers

Some households have multiple telephone lines for voice communication.

The table below provides summary statistics for the number of telephone lines in the monthly sampled households.

Table 1: Number of Telephone Lines per Household

  Value
Mean 1.188
Standard deviation 0.488
Minimum     1
25th percentile     1
Median     1
75th percentile     1
Maximum     4

Specific Weight Adjustment for Number of Eligible Household Members

The probability of selecting an individual respondent depends upon the number of eligible respondents in the household.

The table below provides summary statistics for the number of eligible members in the monthly sampled households.

Table 2: Number of Eligible Household Members

  Value
Mean 2.001
Standard deviation 0.871
Minimum     1
25th percentile     1
Median     2
75th percentile     2
Maximum     9

Post-Stratification Weight Adjustments

Adjusting weighted survey counts so that they agree with population counts provided by the Census Bureau can compensate for different response rates by demographic subgroups, increase the precision of survey estimates, and reduce the bias present in the estimates resulting from the inclusion of only telephone households.

The cells, used to construct post-stratification adjustments for this month, together with the number of sample observations and the national population estimates from the Census Bureau are shown in the table below.

Table 3: Post-Stratification Cells

Cell Description Sample Size Population
1 Male - Hispanic (Any Race)    34  10,167,034
2 Male - Non-Hispanic Black    24   9,883,467
3 Male - Age 18 – 24 - Non-Hispanic White    19   8,635,241
4 Male - Age 25 – 34 - Non-Hispanic White    47  11,985,017
5 Male - Age 35 – 44 - Non-Hispanic White    73  15,833,339
6 Male - Age 45 – 54 - Non-Hispanic White    86  14,165,493
7 Male - Age 55 – 64 - Non-Hispanic White    51   9,215,914
8 Male - Age 65 or older - Non-Hispanic White    57  11,755,768
9 Male - Non-Hispanic Other    18   4,146,032
10 Female - Hispanic (Any Race)    51  10,625,145
11 Female - Age 18 – 44 - Non-Hispanic Black    35   7,307,267
12 Female - Age 45 or older - Non-Hispanic Black    27   5,144,462
13 Female - Age 18 – 24 - Non-Hispanic White    24   8,531,226
14 Female - Age 25 – 34 - Non-Hispanic White    69  12,373,489
15 Female - Age 35 – 44 - Non-Hispanic White    85  16,061,583
16 Female - Age 45 – 54 - Non-Hispanic White    92  14,513,973
17 Female - Age 55 – 64 - Non-Hispanic White    67   9,837,412
18 Female - Age 65 or older - Non-Hispanic White    82  15,762,147
19 Female - Non-Hispanic Other    38   4,762,691
N/A Missing Demographic Information    36     N/A    
TOTAL 1,015 200,706,700

Data Collection Schedule

The survey was conducted over 13 days to enable 1,015 interviews to be completed. The survey period was from February 1 through February 13.

Disposition of Sample Telephone Numbers

The table below presents the distribution of household telephone numbers by disposition categories. The number of household cases in each category was then used to calculate a CASRO response rate of approximately 49 percent.

Table 4: Distribution of Household Cases by Disposition

Disposition Category Number of Households
Telephone Numbers Available 4,715
Telephone Numbers Released 2,930
Telephone Numbers Not Dialed     0
Telephone Numbers Dialed 2,930
Out-of-Scope Numbers (Ineligible)   782
BG - Business   158
CF - Computer/Fax   237
DS - Disconnected number   346
NC - Number change    29
NQ - No one 18 years old or older in household    10
UNB - Unavailable before and during study period     2
Scope Undetermined   336
NA - No answer   232
BZ - Busy     0
AM - Answering machine    64
LM - Left message     1
CCC - Cannot complete call     4
PM - Privacy manager     5
NQL - Eligibility undetermined because of language problems or deafness    12
RFI - Refused to speak with interviewer (screening incomplete)     0
HRI - Hard refusal *     4
OD - Maximum call attempts reached     0
CBU - Callback undetermined    14
CSU - Callback Spanish undetermined     0
In-Scope Numbers 1,812
Complete 1,015
DIP - Reinterview deletion, ineligible person in household interviewed    13
DDA - Reinterview deletion, discrepancy in answers during reinterview     4
CB - Callback   104
CBS - Callback Spanish     0
NAQ - No answer qualified   219
BZQ - Busy qualified     6
AMQ - Answering machine qualified   192
LMQ - Left message qualified     3
CCQ - Cannot complete call qualified     3
PMQ - Privacy manager qualified     1
DL - Deaf/Language    55
RFQ - Respondent refusal    10
UN - Unavailable    16
DR - Respondent deceased prior to completion of interview     0
AC - The area code is changed but not the number     0
HRQ - Hard refusal *   171
CASRO Response Rate 49.59%