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Omnibus Survey Household Survey Month Specific Information August 2003
Month Specific Information
This report provides technical information for the August 2003 Household Survey. Starting in December 2002, the Omnibus Household Surveys are conducted 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 August 2003 survey collected data from August 3, 2003 through August 13, 2003. Data were collected from households in the U.S. using a Random-Digit-Dialed telephone methodology. The final completed sample size is 1,032 cases, and the total number of variables in the public-use dataset is 225. The data were collected by M. Davis and Company (MDAC), under contract with the BTS.
The August 2003 survey collected data from August 8, 2003 through August 22, 2003. Data were collected from households in the U.S. using a Random-Digit-Dialed telephone methodology. The final completed sample size is 1,029 cases, and the total number of variables in the public-use dataset is 240. The data were collected by M. Davis and Company (MDAC), under contract with the BTS.
Sample Telephone Number Selection
There were 6,744 telephone numbers for the August 2003 survey. A total of 4,092 of these numbers were identified as working residential numbers and were divided into 82 replicates. Each of the 66 fielding replicates released initially contained approximately 50 households. Four additional replicates were released during Fielding. Eight (8) unused replicates from August's sample were used to conduct a pretest. Each pretest replicate had approximately 50 households. Four (4) of the 82 August replicates were not utilized in the actual interviewing, resulting in 3,333 numbers being released for use by the telephone interviewers. For this survey, the total number of telephone numbers in the sampling frame, N, is 273,055,800. The total number of telephone numbers in the sample (numbers dialed) was 3,333.
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 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)||32||12,845,409|
|2||Male - Non-Hispanic Black||47||10,224,033|
|3||Male - Age 18 24 - Non-Hispanic White||23||8,499,919|
|4||Male - Age 25 34 - Non-Hispanic White||43||11,913,170|
|5||Male - Age 35 44 - Non-Hispanic White||70||15,039,201|
|6||Male - Age 45 54 - Non-Hispanic White||79||14,623,075|
|7||Male - Age 55 64 - Non-Hispanic White||54||10,048,666|
|8||Male - Age 65 or older - Non-Hispanic White||51||11,929,766|
|9||Male - Non-Hispanic Other||31||5,765,040|
|10||Female - Hispanic (Any Race)||42||12,298,055|
|11||Female - Age 18 44 - Non-Hispanic Black||26||7,460,884|
|12||Female - Age 45 or older - Non-Hispanic Black||28||5,469,299|
|13||Female - Age 18 24 - Non-Hispanic White||22||8,568,517|
|14||Female - Age 25 34 - Non-Hispanic White||56||12,118,904|
|15||Female - Age 35 44 - Non-Hispanic White||104||15,364,818|
|16||Female - Age 45 54 - Non-Hispanic White||95||14,962,740|
|17||Female - Age 55 64 - Non-Hispanic White||73||10,641,416|
|18||Female - Age 65 or older - Non-Hispanic White||85||16,115,329|
|19||Female - Non-Hispanic Other||24||6,464,326|
|N/A||Missing Demographic Information||47||N/A|
Data Collection Schedule
The survey was conducted over 11 days to enable 1,000 interviews to be completed. The survey period was from August 3 through August 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 46 percent.
Table 4: Distribution of Household Cases by Disposition
|Disposition Category||Number of Households|
|Telephone Numbers Available||3,692|
|Telephone Numbers Released||3,333|
|Telephone Numbers Not Dialed||0|
|Telephone Numbers Dialed||3,333|
|Out-of-Scope Numbers (Ineligible)||982|
|BG - Business||244|
|CF - Computer/Fax||268|
|DS - Disconnected number||412|
|NC - Number change||25|
|NQ - No one 18 years old or older in household||14|
|UNB - Unavailable before and during study period||19|
|NA - No answer||328|
|BZ - Busy||1|
|AM - Answering machine||32|
|LM - Left message||3|
|CCC - Cannot complete call||1|
|PM - Privacy manager||9|
|NQL - Eligibility undetermined because of language problems or deafness||7|
|RFI - Refused to speak with interviewer (screening incomplete)||8|
|HRI - Hard refusal *||0|
|OD - Maximum call attempts reached||0|
|CBU - Callback undetermined||33|
|CSU - Callback Spanish undetermined||1|
|DIP - Reinterview deletion, ineligible person in household interviewed||9|
|DDA - Reinterview deletion, discrepancy in answers during reinterview||4|
|CB - Callback||259|
|CBS - Callback Spanish||0|
|NAQ - No answer qualified||321|
|BZQ - Busy qualified||7|
|AMQ - Answering machine qualified||139|
|LMQ - Left message qualified||9|
|CCQ - Cannot complete call qualified||0|
|PMQ - Privacy manager qualified||10|
|DL - Deaf/Language||60|
|RFQ - Respondent refusal||27|
|UN - Unavailable||29|
|DR - Respondent deceased prior to completion of interview||0|
|AC - The area code is changed but not the number||0|
|HRQ - Hard refusal *||22|
|CASRO Response Rate||46.73%|