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Omnibus Survey Household Survey Results Month Specific Information August 2001Specific Weight Adjustment for Number of Eligible Household Members
Household Survey Results
Month Specific Information
This report presents the results of the August 2001 Household Survey. Each 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 each month that correspond to one of DOT's 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 in each survey and will vary from month to month.
The August 2001 survey collected data between August 4, 2001 and August 13, 2001. Data were collected from households in the U.S. using a Random-Digit-Dialed telephone methodology. The final completed sample size is 1,038 cases, and the total number of variables in the public-use dataset is 203. The data were collected by M. Davis and Company, under contract with the BTS.
Sample Telephone Number Selection
There were 11,271 telephone numbers purchased for the August 2001 survey. A total of 6,893 of these numbers were identified as working residential numbers and were divided into 69 replicates. Each replicate contained approximately 100 households. Four of the replicates were used to conduct a pretest and 44 replicates were used for the actual interviewing. Twenty-Five (25) (includes the 4 replicates used for the pretest) of the 69 replicates were not utilized in the actual interviewing, resulting in 4,462 numbers being released for use by the telephone interviewers.
For this months survey, the total number of telephone numbers in the sampling frame, N, is 257,144,100. The total number of telephone numbers in the sample (numbers dialed) is 4,342.
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)||45||10,167,034|
|2||Male NonHispanic Black||34||9,883,467|
|3||Male Age 18 24 NonHispanic White||37||8,635,241|
|4||Male Age 25 34 NonHispanic White||60||11,985,017|
|5||Male Age 35 44 NonHispanic White||78||15,833,339|
|6||Male Age 45 54 NonHispanic White||72||14,165,493|
|7||Male Age 55 64 NonHispanic White||34||9,215,914|
|8||Male Age 65 or older NonHispanic White||70||11,755,768|
|9||Male NonHispanic Other||32||4,146,032|
|10||Female Hispanic (Any Race)||32||10,625,145|
|11||Female Age 18 44 NonHispanic Black||32||7,307,267|
|12||Female Age 45 or older NonHispanic Black||32||5,144,462|
|13||Female Age 18 24 NonHispanic White||27||8,531,226|
|14||Female Age 25 34 NonHispanic White||66||12,373,489|
|15||Female Age 35 44 Non-Hispanic White||91||16,061,583|
|16||Female Age 45 54 NonHispanic White||80||14,513,973|
|17||Female Age 55 64 NonHispanic White||62||9,837,412|
|18||Female Age 65 or older NonHispanic White||97||15,762,147|
|19||Female NonHispanic Other||26||4,762,691|
|N/A||Missing Demographic Information||31||N/A|
Data Collection Schedule
The survey was conducted over a ten-day period, from August 4, 2001 through August 13, 2001. A total of 1,038 interviews were completed during the survey period.
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 35 percent.
Table 4: Distribution of Household Cases by Disposition
|Disposition Category||Number of Households|
|Telephone Numbers Available||6,850|
|Telephone Numbers Released||4,462|
|Telephone Numbers Not Dialed||120|
|Telephone Numbers Dialed||4,342|
|Out-of-Scope Numbers (Ineligible)||953|
|BG - Business||238|
|CF - Computer/Fax||229|
|DS - Disconnected number||428|
|NC - Number change||40|
|NQ - No one 18 years old or older in household||6|
|UNB - Unavailable before and during study period||12|
|NA - No answer||462|
|BZ - Busy||2|
|AM - Answering machine||155|
|CCC - Cannot complete call||0|
|PM - Privacy manager||46|
|NQL - Eligibility undetermined because of language problems or deafness||19|
|RFI - Refused to speak with interviewer (screening incomplete)||72|
|HRI - Initial Refusal - Requested name be removed from calling list||498|
|OD - Maximum call attempts reached||103|
|CB - Callback||221|
|CBS - Callback Spanish||14|
|NAQ - No Answer Qualified||222|
|BZQ - Busy Qualified||15|
|AMQ - Answering Machine Qualified||176|
|LMQ - Left Message Qualified||0|
|CCQ - Cannot Complete Call Qualified||0|
|PMQ - Privacy Manager Qualified||7|
|DL - Deaf/Language||57|
|RFQ - Respondent refusal||8|
|UN - Unavailable||80|
|DR - Respondent deceased prior to completion of interview||1|
|AC - The area code is changed but not the number||0|
|HRQ - Qualified Refusal - Requested name be removed from calling list||176|
|CASRO Response Rate||35.12%|