You are here

Omnibus Survey Household Survey Results Specific Methodology October 2000

Omnibus Survey
Household Survey Results
Specific Methodology
October 2000


Data collection for October 2000 Omnibus Household Survey began on October 4, 2000, and continued until October 10, 2000. Calls were placed between 9:00 a.m. and 9:00 p.m. local time in all regions of the country. Approximately 90 interviewers were trained for the study. Data was collected from households in the U.S. using a random-digit-dialed telephone survey method. The final data set includes 1,269 completed cases and a total of 147 variables. Battelle collected the data under contract with the Bureau of Transportation Statistics.

For this survey, 15,519 telephone numbers (in replicates of approximately 500) were purchased from Marketing Systems Group's (Ft. Washington, PA) GENESYS Sampling System. Of these, 10,000 were identified as working, residential telephone numbers. Five of the sample replicates were not needed, resulting in 7,525 numbers being released for use by the telephone interviewers. For this survey, the total number of telephone numbers in the sampling frame was 246,870,500.

Response Rates

The procedure for response rate calculation is based on the guidelines established by the Council of American Survey Research Organizations (CASRO). The final response rate for the survey was obtained using the following formula:

Response rate equals completed household interviews divided by outer left parenthesis households in scope plus inner left parenthesis scope undetermined times left brace households in scope divided by households in and out of scope right brace inner right parenthesis outer right parenthesis

Distribution of household telephone numbers by disposition categories is presented in Table 1 below. The number of household cases in each category was then used in the above formula to calculate an overall response rate of approximately 24 percent.

Table 1. Distribution of Household Cases by Disposition Code

Household Level Results
Number of Telephone Numbers Released 7,525
Number of Pending Cases (Number not Dialed)     0
Number of Household Cases Worked 7,525
Number of Out of Scope Numbers (ineligible) 1,769
Number of No Contact (Scope Undetermined) 1,408
Number of Households in Scope 4,348
Number of Completes 1,269
Number of Partial Completes    51
Number of Language Problem   217
Number of Not Screened   173
Number of Refusal 2,129
Number of Parental Refusal     6
Number of Respondent Identified, Case not Finalized   305
Number of Unavailable During Study Period   198
Household Response Rate  23.7%

Follow-up efforts were limited to six attempts to determine whether a telephone number was residential, an additional five attempts to identify an eligible respondent, and a final five attempts to secure a completed interview or refusal. Therefore, the maximum number of call attempts to any household was sixteen. Once contact was made with a household, follow-up attempts followed a loose call-back schedule established at the initial contact. That is, good times and days to call back were requested at the initial contact, but follow-up calls also were attempted before these appointment times, unless told otherwise not to do so by the household. This allowed for making the maximum number of attempts within the study period.

The October Survey employed a limited experiment during the period of October 6-8, 2000 to examine methodologies to increase response rates. Three highly experienced refusal conversion specialists attempted to complete the interview with 256 households that had previously refused to participate. From those attempts, three households completed the survey.


Prior to the start of actual data collection, a pretest was conducted to test the usability of the survey instrument. Particular focus was placed on testing questions that were new to the October survey. Qualified data collection and data preparation staff performed this pretest by first reviewing the questionnaire and then using it in simulated data collection situations. They looked for vague or confusing instructions, inconsistent questions or answer categories, incomplete or redundant sections, and poor pace, tone, flow, and format of questions. They also tested the interview length and determined that the survey questionnaire could be administered in approximately 15 minutes.

Pre-Contact Letter

No pre-contact letter was mailed for the October survey.