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Omnibus Survey Household Survey Month Specific Information April 2003
Month Specific Information
This report presents the results of the April 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 April 2003 survey collected data from April 6, 2003 through April 17, 2003. Data were collected from households in the U.S. using a Random-Digit-Dialed telephone methodology. The final completed sample size is 1,021 cases, and the total number of variables in the public-use dataset is 214. The data were collected by M. Davis and Company (MDAC), under contract with the BTS.
Sample Telephone Number Selection
There were 8,200 telephone numbers for the April 2003 survey. A total of 5,163 of these numbers were identified as working residential numbers and were divided into 103 replicates. Each of the 61 fielding replicates released initially contained approximately 50 households. Two additional replicates were released during Fielding. Eight (8) unused replicates from April's sample were used to conduct a pretest. Each pretest replicate had approximately 50 households. Thirty-four (34) of the 103 April replicates were not utilized in the actual interviewing, resulting in 3,160 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 3,160.
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
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
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
|1||Male - Hispanic (Any Race)||36||10,167,034|
|2||Male - Non-Hispanic Black||27||9,883,467|
|3||Male - Age 18 24 - Non-Hispanic White||27||8,635,241|
|4||Male - Age 25 34 - Non-Hispanic White||57||11,985,017|
|5||Male - Age 35 44 - Non-Hispanic White||66||15,833,339|
|6||Male - Age 45 54 - Non-Hispanic White||86||14,165,493|
|7||Male - Age 55 64 - Non-Hispanic White||56||9,215,914|
|8||Male - Age 65 or older - Non-Hispanic White||47||11,755,768|
|9||Male - Non-Hispanic Other||27||4,146,032|
|10||Female - Hispanic (Any Race)||45||10,625,145|
|11||Female - Age 18 44 - Non-Hispanic Black||34||7,307,267|
|12||Female - Age 45 or older - Non-Hispanic Black||25||5,144,462|
|13||Female - Age 18 24 - Non-Hispanic White||13||8,531,226|
|14||Female - Age 25 34 - Non-Hispanic White||50||12,373,489|
|15||Female - Age 35 44 - Non-Hispanic White||88||16,061,583|
|16||Female - Age 45 54 - Non-Hispanic White||88||14,513,973|
|17||Female - Age 55 64 - Non-Hispanic White||48||9,837,412|
|18||Female - Age 65 or older - Non-Hispanic White||103||15,762,147|
|19||Female - Non-Hispanic Other||34||4,762,691|
|N/A||Missing Demographic Information||64||N/A|
Data Collection Schedule
The survey was conducted over 12 days to enable at least 1,000 interviews to be completed. The survey period was from April 6 through April 17.
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 46 percent.
Table 4: Distribution of Household Cases by Disposition
|Disposition Category||Number of Households|
|Telephone Numbers Available||4,762|
|Telephone Numbers Released||3,160|
|Telephone Numbers Not Dialed||0|
|Telephone Numbers Dialed||3,160|
|Out-of-Scope Numbers (Ineligible)||832|
|BG - Business||191|
|CF - Computer/Fax||224|
|DS - Disconnected number||376|
|NC - Number change||21|
|NQ - No one 18 years old or older in household||8|
|UNB - Unavailable before and during study period||12|
|NA - No answer||305|
|BZ - Busy||0|
|AM - Answering machine||57|
|LM - Left message||0|
|CCC - Cannot complete call||4|
|PM - Privacy manager||14|
|NQL - Eligibility undetermined because of language problems or deafness||15|
|RFI - Refused to speak with interviewer (screening incomplete)||2|
|HRI - Hard refusal *||0|
|OD - Maximum call attempts reached||0|
|CBU - Callback undetermined||2|
|CSU - Callback Spanish undetermined||0|
|DIP - Reinterview deletion, ineligible person in household interviewed||2|
|DDA - Reinterview deletion, discrepancy in answers during reinterview||5|
|CB - Callback||220|
|CBS - Callback Spanish||1|
|NAQ - No answer qualified||336|
|BZQ - Busy qualified||0|
|AMQ - Answering machine qualified||187|
|LMQ - Left message qualified||3|
|CCQ - Cannot complete call qualified||3|
|PMQ - Privacy manager qualified||7|
|DL - Deaf/Language||53|
|RFQ - Respondent refusal||12|
|UN - Unavailable||27|
|DR - Respondent deceased prior to completion of interview||0|
|AC - The area code is changed but not the number||0|
|HRQ - Hard refusal *||52|
|CASRO Response Rate||46.25%|