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Omnibus Survey Household Survey Results Month Specific Information March 2002

Omnibus Survey
Household Survey Results
Month Specific Information
March 2002

This report presents the results of the March 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 March 2002 survey collected data between March 2, 2002 and March 11, 2002. Data were collected from households in the U.S. using a Random-Digit-Dialed telephone methodology. The final completed sample size is 1,007 cases, and the total number of variables in the public-use dataset is 180. The data were collected by M. Davis and Company, under contract with the BTS.

Sample Telephone Number Selection

There were 8,200 telephone numbers purchased for the March 2002 survey. A total of 5,152 of these numbers were identified as working residential numbers and were divided into 52 replicates. Each replicate contained approximately 100 households. Four (4) unused replicates from March's sample were used to conduct a pretest. Twelve of the 52 March replicates were not utilized in the actual interviewing, resulting in 3,645 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 262,863,400. The total number of telephone numbers in the sample (numbers dialed) is 3,645.

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 1.147
Standard deviation 0.423
Minimum     1
25th percentile     1
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 1.904
Standard deviation 0.772
Minimum     1
25th percentile     1
Median     2
75th percentile     2
Maximum     6

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)    25  10,167,034
2 Male - Non-Hispanic Black    35   9,883,467
3 Male - Age 18 - 24 - Non-Hispanic White    30   8,635,241
4 Male - Age 25 - 34 - Non-Hispanic White    57  11,985,017
5 Male - Age 35 - 44 - Non-Hispanic White    79  15,833,339
6 Male - Age 45 - 54 - Non-Hispanic White    77  14,165,493
7 Male - Age 55 - 64 - Non-Hispanic White    46   9,215,914
8 Male - Age 65 or older - Non-Hispanic White    43  11,755,768
9 Male - Non-Hispanic Other    27   4,146,032
10 Female - Hispanic (Any Race)    42  10,625,145
11 Female - Age 18 - 44 - Non-Hispanic Black    45   7,307,267
12 Female - Age 45 or older - Non-Hispanic Black    26   5,144,462
13 Female - Age 18 - 24 - Non-Hispanic White    15   8,531,226
14 Female - Age 25 - 34 - Non-Hispanic White    58  12,373,489
15 Female - Age 35 - 44 - Non-Hispanic White   106  16,061,583
16 Female - Age 45 - 54 - Non-Hispanic White    84  14,513,973
17 Female - Age 55 - 64 - Non-Hispanic White    58   9,837,412
18 Female - Age 65 or older - Non-Hispanic White    90  15,762,147
19 Female - Non-Hispanic Other    38   4,762,691
N/A Missing Demographic Information    26     N/A    
TOTAL 1,007 200,706,700

Data Collection Schedule

The survey was conducted over a ten-day period, from March 2, 2002 through March 11, 2002. A total of 1,007 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 39 percent.

Table 4: Distribution of Household Cases by Disposition

Disposition Category Number of Households
Telephone Numbers Available 4,746
Telephone Numbers Released 3,645
Telephone Numbers Not Dialed     0
Telephone Numbers Dialed 3,645
Out-of-Scope Numbers (Ineligible)   811
BG - Business   170
CF - Computer/Fax   141
DS - Disconnected number   458
NC - Number change    16
NQ - No one 18 years old or older in household    12
UNB - Unavailable before and during study period    14
Scope Undetermined  918
NA - No answer   434
BZ - Busy     0
AM - Answering machine   141
LM - Left message     6
CCC - Cannot complete call     5
PM - Privacy manager    29
NQL - Eligibility undetermined because of language problems or deafness    45
RFI - Refused to speak with interviewer (screening incomplete)    85
HRI - Hard refusal   173
OD - Maximum call attempts reached     0
In-Scope Numbers 1,916
Complete 1,007
Partial Complete    15
CB - Callback   204
CBS - Callback Spanish    10
NAQ - No Answer Qualified   295
BZQ - Busy Qualified     4
AMQ - Answering Machine Qualified   214
LMQ - Left Message Qualified    20
CCQ - Cannot Complete Call Qualified     3
PMQ - Privacy Manager Qualified     7
DL - Deaf/Language    56
RFQ - Respondent refusal     2
UN - Unavailable    51
DR - Respondent deceased prior to completion of interview     0
AC - The area code is changed but not the number     0
HRQ - Hard refusal    28
CASRO Response Rate 39.32%