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Omnibus Survey Household Survey Results Month Specific Information October 2001

Omnibus Survey
Household Survey Results
Month Specific Information
October 2001

This report presents the results of the October 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 October 2001 survey collected data between October 6, 2001 and October 16, 2001. Data were collected from households in the U.S. using a Random-Digit-Dialed telephone methodology. The final completed sample size is 1,023 cases, and the total number of variables in the public-use dataset is 208. 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 October 2001 survey. A total of 11,271 of these numbers were identified as working residential numbers and were divided into 7,262,73 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 nine (29) (includes the 4 replicates used for the pretest) of the 7,262,73 replicates were not utilized in the actual interviewing, resulting in 4,380 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 4,155.

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

  Value
Mean 1.206
Standard deviation 0.595
Minimum     1
25th percentile    11
Median     1
75th percentile     1
Maximum     5

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

  Value
Mean 1.997
Standard deviation 0.823
Minimum     1
25th percentile     2
Median     2
75th percentile     2
Maximum     7

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

Cell Description Sample Size Population
1 Male - Hispanic (Any Race)    27  10,167,034
2 Male - Non-Hispanic Black    34   9,883,467
3 Male - Age 18 - 24 - Non-Hispanic White    17   8,635,241
4 Male - Age 25 - 34 - Non-Hispanic White    75  11,985,017
5 Male - Age 35 - 44 - Non-Hispanic White    87  15,833,339
6 Male - Age 45 - 54 - Non-Hispanic White    73  14,165,493
7 Male - Age 55 - 64 - Non-Hispanic White    39   9,215,914
8 Male - Age 65 or older - Non-Hispanic White    51  11,755,768
9 Male - Non-Hispanic Other    38   4,146,032
10 Female - Hispanic (Any Race)    36  10,625,145
11 Female - Age 18 - 44 - Non-Hispanic Black    32   7,307,267
12 Female - Age 45 or older - Non-Hispanic Black    25   5,144,462
13 Female - Age 18 - 24 - Non-Hispanic White    26   8,531,226
14 Female - Age 25 - 34 - Non-Hispanic White    68  12,373,489
15 Female - Age 35 - 44 - Non-Hispanic White    98  16,061,583
16 Female - Age 45 - 54 - Non-Hispanic White    83  14,513,973
17 Female - Age 55 - 64 - Non-Hispanic White    69   9,837,412
18 Female - Age 65 or older - Non-Hispanic White    91  15,762,147
19 Female - Non-Hispanic Other    41   4,762,691
N/A Missing Demographic Information    13     N/A    
TOTAL 1,023 200,706,700

Data Collection Schedule

The survey was conducted over a ten-day period, from October 6, 2001 through October 16, 2001. A total of 1,023 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 6,864
Telephone Numbers Released 4,380
Telephone Numbers Not Dialed   225
Telephone Numbers Dialed 4,155
Out-of-Scope Numbers (Ineligible)   922
BG - Business   204
CF - Computer/Fax   175
DS - Disconnected number   498
NC - Number change    23
NQ - No one 18 years old or older in household     8
UNB - Unavailable before and during study period    14
Scope Undetermined 1,096
NA - No answer   463
BZ - Busy    10
AM - Answering machine   166
CCC - Cannot complete call     0
PM - Privacy manager    28
NQL - Eligibility undetermined because of language problems or deafness    12
RFI - Refused to speak with interviewer (screening incomplete)   126
HRI - Initial Refusal - Requested name be removed from calling list   276
OD - Maximum call attempts reached    15
In-Scope Numbers 2,137
Complete 1,023
Partial Complete    23
CB - Callback   373
CBS - Callback Spanish     7
NAQ - No Answer Qualified   324
BZQ - Busy Qualified     8
AMQ - Answering Machine Qualified   155
LMQ - Left Message Qualified     0
CCQ - Cannot Complete Call Qualified     0
PMQ - Privacy Manager Qualified     4
DL - Deaf/Language    57
RFQ - Respondent refusal    43
UN - Unavailable    37
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    83
CASRO Response Rate 35.24%