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Omnibus Survey Household Survey Results Month Specific Information January 2002

Omnibus Survey
Household Survey Results
Month Specific Information
January 2002

This report presents the results of the January 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 January 2002 survey collected data between January 5, 2002 and January 14, 2002. Data were collected from households in the U.S. using a Random-Digit-Dialed telephone methodology. The final completed sample size is 1,142 cases, and the total number of variables in the public-use dataset is 203. 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 January 2002 survey. A total of 6,737 of these numbers were identified as working residential numbers and were divided into 67,67 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-five (25) (includes the 4 replicates used for the pretest) of the 67,67 replicates were not utilized in the actual interviewing, resulting in 3,827 numbers being released for use by the telephone interviewers.

For this 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 3,810.

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 1.180
Standard deviation 0.508
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 1.985
Standard deviation 0.884
Minimum     1
25th percentile     1
Median     2
75th percentile     2
Maximum    11

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)    36  10,167,034
2 Male - Non-Hispanic Black    25   9,883,467
3 Male - Age 18 - 24 - Non-Hispanic White    29   8,635,241
4 Male - Age 25 - 34 - Non-Hispanic White    63  11,985,017
5 Male - Age 35 - 44 - Non-Hispanic White    86  15,833,339
6 Male - Age 45 - 54 - Non-Hispanic White    75  14,165,493
7 Male - Age 55 - 64 - Non-Hispanic White    61   9,215,914
8 Male - Age 65 or older - Non-Hispanic White    70  11,755,768
9 Male - Non-Hispanic Other    46   4,146,032
10 Female - Hispanic (Any Race)    53  10,625,145
11 Female - Age 18 - 44 - Non-Hispanic Black    34   7,307,267
12 Female - Age 45 or older - Non-Hispanic Black    31   5,144,462
13 Female - Age 18 - 24 - Non-Hispanic White    38   8,531,226
14 Female - Age 25 - 34 - Non-Hispanic White    88  12,373,489
15 Female - Age 35 - 44 - Non-Hispanic White    89  16,061,583
16 Female - Age 45 - 54 - Non-Hispanic White    89  14,513,973
17 Female - Age 55 - 64 - Non-Hispanic White    66   9,837,412
18 Female - Age 65 or older - Non-Hispanic White   104  15,762,147
19 Female - Non-Hispanic Other    41   4,762,691
N/A Missing Demographic Information    18     N/A    
TOTAL 1,142 200,706,700

Data Collection Schedule

The survey was conducted over a ten-day period, from January 5, 2002 through January 14, 2002. A total of 1,142 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 39.5 percent.

Table 4: Distribution of Household Cases by Disposition

Disposition Category Number of Households
Telephone Numbers Available 6,335
Telephone Numbers Released 3,827
Telephone Numbers Not Dialed    17
Telephone Numbers Dialed 3,810
Out-of-Scope Numbers (Ineligible)   689
BG - Business   159
CF - Computer/Fax   117
DS - Disconnected number   369
NC - Number change    15
NQ - No one 18 years old or older in household     6
UNB - Unavailable before and during study period    23
Scope Undetermined  959
NA - No answer   427
BZ - Busy     0
AM - Answering machine   213
LM - Left message     3
CCC - Cannot complete call     0
PM - Privacy manager    34
NQL - Eligibility undetermined because of language problems or deafness    20
RFI - Refused to speak with interviewer (screening incomplete)    24
HRI - Initial Refusal - Requested name be removed from calling list   238
OD - Maximum call attempts reached     0
In-Scope Numbers 2,162
Complete 1,142
Partial Complete    26
CB - Callback   265
CBS - Callback Spanish    10
NAQ - No Answer Qualified   285
BZQ - Busy Qualified     0
AMQ - Answering Machine Qualified   247
LMQ - Left Message Qualified    10
CCQ - Cannot Complete Call Qualified     0
PMQ - Privacy Manager Qualified    30
DL - Deaf/Language    51
RFQ - Respondent refusal     3
UN - Unavailable    86
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    34
CASRO Response Rate 39.53%