This report presents the results of the December 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 December 2001 survey collected data between December 1, 2001 and December 10, 2001. Data were collected from households in the U.S. using a Random-Digit-Dialed telephone methodology. The final completed sample size is 1,083 cases, and the total number of variables in the public-use dataset is 258. The data were collected by M. Davis and Company, under contract with the BTS.
There were 11,271 telephone numbers purchased for the December 2001 survey. A total of 6,931 of these numbers were identified as working residential numbers and were divided into 70 replicates. Each replicate contained approximately 100 households. Four (4) unused replicates from December 2001's sample were used to conduct a pretest. Twenty-five (25) of the 70 December replicates were not utilized in the actual interviewing, resulting in 4,456 numbers being released for use by the telephone interviewers.
For this month's survey, the total number of telephone numbers in the sampling frame, N, is 260,828,700. The total number of telephone numbers in the sample (numbers dialed) is 4,454.
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.
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.
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.
|1||Male - Hispanic (Any Race)||38||10,167,034|
|2||Male - Non-Hispanic Black||27||9,883,467|
|3||Male - Age 18 - 24 - Non-Hispanic White||31||8,635,241|
|4||Male - Age 25 - 34 - Non-Hispanic White||62||11,985,017|
|5||Male - Age 35 - 44 - Non-Hispanic White||88||15,833,339|
|6||Male - Age 45 - 54 - Non-Hispanic White||72||14,165,493|
|7||Male - Age 55 - 64 - Non-Hispanic White||55||9,215,914|
|8||Male - Age 65 or older - Non-Hispanic White||69||11,755,768|
|9||Male - Non-Hispanic Other||24||4,146,032|
|10||Female - Hispanic (Any Race)||44||10,625,145|
|11||Female - Age 18 - 44 - Non-Hispanic Black||28||7,307,267|
|12||Female - Age 45 or older - Non-Hispanic Black||16||5,144,462|
|13||Female - Age 18 - 24 - Non-Hispanic White||35||8,531,226|
|14||Female - Age 25 - 34 - Non-Hispanic White||73||12,373,489|
|15||Female - Age 35 - 44 - Non-Hispanic White||96||16,061,583|
|16||Female - Age 45 - 54 - Non-Hispanic White||75||14,513,973|
|17||Female - Age 55 - 64 - Non-Hispanic White||76||9,837,412|
|18||Female - Age 65 or older - Non-Hispanic White||116||15,762,147|
|19||Female - Non-Hispanic Other||39||4,762,691|
|N/A||Missing Demographic Information||19||N/A|
The survey was conducted over a ten-day period, from December 1, 2001 through December 10, 2001. A total of 1,083 interviews were completed during the survey period.
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 33.8 percent.
|Disposition Category||Number of Households|
|Telephone Numbers Available||6,535|
|Telephone Numbers Released||4,456|
|Telephone Numbers Not Dialed||2|
|Telephone Numbers Dialed||4,454|
|Out-of-Scope Numbers (Ineligible)||842|
|BG - Business||224|
|CF - Computer/Fax||153|
|DS - Disconnected number||419|
|NC - Number change||21|
|NQ - No one 18 years old or older in household||9|
|UNB - Unavailable before and during study period||16|
|NA - No answer||606|
|BZ - Busy||1|
|AM - Answering machine||219|
|LM - Left message||1|
|CCC - Cannot complete call||0|
|PM - Privacy manager||124|
|NQL - Eligibility undetermined because of language problems or deafness||15|
|RFI - Refused to speak with interviewer (screening incomplete)||133|
|HRI - Initial Refusal - Requested name be removed from calling list||337|
|OD - Maximum call attempts reached||8|
|CB - Callback||222|
|CBS - Callback Spanish||5|
|NAQ - No Answer Qualified||294|
|BZQ - Busy Qualified||2|
|AMQ - Answering Machine Qualified||195|
|LMQ - Left Message Qualified||5|
|CCQ - Cannot Complete Call Qualified||0|
|PMQ - Privacy Manager Qualified||72|
|DL - Deaf/Language||61|
|RFQ - Respondent refusal||16|
|UN - Unavailable||75|
|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||113|
|CASRO Response Rate||33.76%|