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Omnibus Survey Household Survey Month Specific Information July 2002
Month Specific Information
This report presents the results of the July 2002 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 July 2002 survey collected data from July 13, 2002 through July 22, 2002. Data were collected from households in the U.S. using a Random-Digit-Dialed telephone methodology. The final completed sample size is 1,079 cases, and the total number of variables in the public-use dataset is 146. 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 purchased for the July 2002 survey. A total of 5,212 of these numbers were identified as working residential numbers and were divided into 104 replicates. Each of the 70 fielding replicates released initially contained approximately 50 households. No additional replicates were released during Fielding. Eight (8) unused replicates from July's sample were used to conduct a pretest. Each pretest replicate had approximately 50 households. Twenty-six (26) of the 104 July replicates were not utilized in the actual interviewing, resulting in 3,512 numbers being released for use by the telephone interviewers. For this survey, the total number of telephone numbers in the sampling frame, N, is 261,905,600. The total number of telephone numbers in the sample (numbers dialed) is 3,512.
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)||46||10,167,034|
|2||Male - Non-Hispanic Black||40||9,883,467|
|3||Male - Age 18 - 24 - Non-Hispanic White||27||8,635,241|
|4||Male - Age 25 - 34 - Non-Hispanic White||66||11,985,017|
|5||Male - Age 35 - 44 - Non-Hispanic White||93||15,833,339|
|6||Male - Age 45 - 54 - Non-Hispanic White||87||14,165,493|
|7||Male - Age 55 - 64 - Non-Hispanic White||39||9,215,914|
|8||Male - Age 65 or older - Non-Hispanic White||47||11,755,768|
|9||Male - Non-Hispanic Other||39||4,146,032|
|10||Female - Hispanic (Any Race)||51||10,625,145|
|11||Female - Age 18 - 44 - Non-Hispanic Black||28||7,307,267|
|12||Female - Age 45 or older - Non-Hispanic Black||25||5,144,462|
|13||Female - Age 18 - 24 - Non-Hispanic White||34||8,531,226|
|14||Female - Age 25 - 34 - Non-Hispanic White||50||12,373,489|
|15||Female - Age 35 - 44 - Non-Hispanic White||85||16,061,583|
|16||Female - Age 45 - 54 - Non-Hispanic White||95||14,513,973|
|17||Female - Age 55 - 64 - Non-Hispanic White||72||9,837,412|
|18||Female - Age 65 or older - Non-Hispanic White||95||15,762,147|
|19||Female - Non-Hispanic Other||37||4,762,691|
|N/A||Missing Demographic Information||23||N/A|
Data Collection Schedule
The survey was conducted over a ten-day period, from July 13, 2002 through July 22, 2002. A total of 1,079 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 in the above formula to calculate an overall response rate of approximately 44.6 percent.
Table 4: Distribution of Household Cases by Disposition
|Disposition Category||Number of Households|
|Telephone Numbers Available||4,812|
|Telephone Numbers Released||3,512|
|Telephone Numbers Not Dialed||0|
|Telephone Numbers Dialed||3,512|
|Out-of-Scope Numbers (Ineligible)||890|
|BG - Business||197|
|CF - Computer/Fax||298|
|DS - Disconnected number||336|
|NC - Number change||23|
|NQ - No one 18 years old or older in household||12|
|UNB - Unavailable before and during study period||24|
|NA - No answer||333|
|BZ - Busy||0|
|AM - Answering machine||82|
|LM - Answering machine||10|
|CCC - Cannot complete call||2|
|PM - Privacy manager||23|
|NQL - Eligibility undetermined: language problems or deafness||55|
|RFI - Refused to speak with interviewer (screening incomplete)||49|
|HRI - Initial Refusal - Requested name be removed from calling list||101|
|OD - Maximum call attempts reached||0|
|NAQ - No Answer Qualified||313|
|BZQ - Busy Qualified||2|
|AMQ - Answering Machine Qualified||200|
|LMQ - Left Message Qualified||16|
|CCQ - Cannot Complete Call Qualified||2|
|PMQ - Privacy Manager Qualified||9|
|CB - Callback||185|
|CBS - Callback Spanish||0|
|DL - Deaf/Language||56|
|RFQ - Respondent refusal||6|
|UN - Unavailable||49|
|DR - Respondent deceased prior to completion of interview||0|
|AC - The area code is changed but not the number||0|
|HRQ - Qualified Refusal - Requested name be removed from calling list||22|
|CASRO Response Rate||44.6%|
*Note: Beginning in March 2002, and for all future months, to more accurately reflect the breadth of cases that fall within the HRI and HRQ categories the words "Hard Refusal" have replaced the words "Requested name be removed from calling list".