This report presents the results of the July 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 July 2001 survey collected data between July 07 and July 16. Data were collected from households in the U.S. using a Random-Digit-Dialed telephone methodology. The final completed sample size is 1,004 cases, and the total number of variables in the public-use dataset is 204. The data were collected by M. Davis and Company, under contract with the BTS.
There were 11,271 telephone numbers purchased for the July 2001 survey. A total of 6.994 of these numbers were identified as working residential numbers and were divided into 70 replicates. Each replicate contained approximately 100 households. Four of the replicates were used to conduct a pretest and 46 replicates were used for the actual interviewing. Twenty four (24) (includes the 4 replicates used for the pretest) of the 70 replicates were not utilized in the actual interviewing. Thus 4,567 numbers were released for use by the telephone interviewers.
For this 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 4,405.
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)||27||10,167,034|
|2||Male - Non-Hispanic Black||39||9,883,467|
|3||Male - Age 18 - 24 - Non-Hispanic White||24||8,635,241|
|4||Male - Age 25 - 34 - Non-Hispanic White||53||11,985,017|
|5||Male - Age 35 - 44 - Non-Hispanic White||79||15,833,339|
|6||Male - Age 45 - 54 - Non-Hispanic White||66||14,165,493|
|7||Male - Age 55 - 64 - Non-Hispanic White||47||9,215,914|
|8||Male - Age 65 or older - Non-Hispanic White||63||11,755,768|
|9||Male - Non-Hispanic Other||32||4,146,032|
|10||Female - Hispanic (Any Race)||32||10,625,145|
|11||Female - Age 18 - 44 - Non-Hispanic Black||31||7,307,267|
|12||Female - Age 45 or older - Non-Hispanic Black||30||5,144,462|
|13||Female - Age 18 - 24 - Non-Hispanic White||31||8,531,226|
|14||Female - Age 25 - 34 - Non-Hispanic White||73||12,373,489|
|15||Female - Age 35 - 44 - Non-Hispanic White||74||16,061,583|
|16||Female - Age 45 - 54 - Non-Hispanic White||72||14,513,973|
|17||Female - Age 55 - 64 - Non-Hispanic White||68||9,837,412|
|18||Female - Age 65 or older - Non-Hispanic White||102||15,762,147|
|19||Female - Non-Hispanic Other||41||4,762,691|
|N/A||Missing Demographic Information||20||N/A|
The survey was conducted over a ten-day period, from July 07 through July 16. A total of 1,004 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 34 percent.
|Disposition Category||Number of Households|
|Telephone Numbers Released||4,567|
|Telephone Numbers Dialed||4,405|
|Out-of-Scope Numbers (Ineligible)||995|
|BG - Business||295|
|CF - Computer/Fax||175|
|DS - Disconnected Number||449|
|NC - Number Change||36|
|NQ - No one 18 years old or older in household||13|
|UNB - Unavailable before and during study period||27|
|NA - No answer||472|
|BZ - Busy||1|
|AM - Answering Machine||172|
|CCC - Cannot complete call||72|
|PM - Privacy Manager||54|
|NQL - Eligibility undetermined because of language problems or deafness||23|
|RFI - Refused to speak with interviewer (screening incomplete)||54|
|HRI - Requested Name be removed from calling list||359|
|OD - Maximum call attempts reached||162|
|In Scope Numbers||2,041|
|CB - Callback||232|
|CBS - Callback Spanish||56|
|NAQ - No Answer Qualified||296|
|BZQ - Busy Qualified||3|
|AMQ - Answering Machine Qualified||217|
|LMQ - Left Message Qualified||0|
|CCQ - Cannot Complete Call Qualified||0|
|PMQ - Privacy Manager Qualified||4|
|DL - Deaf/Language||47|
|RFQ - Respondent Refusal||3|
|UN - Unavailable||79|
|DR - Respondent deceased prior to completion of interview||0|
|AC - The area code is changed but not the number||0|
|HRQ - Requested name be removed from calling list||86|
|CASRO Response Rate||33.90%|