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Omnibus Survey Household Survey Month Specific Information October 2002

Omnibus Survey
Household Survey
Month Specific Information
October 2002

This report presents the results of the October 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 October 2002 survey collected data from October 05, 2002 through October 15, 2002. Data were collected from households in the U.S. using a Random-Digit-Dialed telephone methodology. The final completed sample size is 1,083 cases, and the total number of variables in the public-use dataset is 167. The data were collected by M. Davis and Company (MDAC), under contract with the BTS.

Sample Telephone Number Selection

There were 8,200 telephone numbers for the October 2002 survey. A total of 5,138 of these numbers were identified as working residential numbers and were divided into 103 replicates. Each of the 64 fielding replicates released initially contained approximately 50 households. No additional replicates were released during fielding. Eight (8) unused replicates from October’s sample were used to conduct a pretest. Each pretest replicate had approximately 50 households. Thirty one (31) of the 103 October replicates were not utilized in the actual interviewing, resulting in 3,190 numbers being released for use by the telephone interviewers. For this survey, the total number of telephone numbers in the sampling frame, N, is 266,879,000. The total number of telephone numbers in the sample (numbers dialed) is 3,190.

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 1.191
Standard deviation 0.514
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 1.942
Standard deviation 0.784
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)    45  10,167,034
2 Male - Non-Hispanic Black    37   9,883,467
3 Male - Age 18 – 24 - Non-Hispanic White    25   8,635,241
4 Male - Age 25 – 34 - Non-Hispanic White    60  11,985,017
5 Male - Age 35 – 44 - Non-Hispanic White    83  15,833,339
6 Male - Age 45 – 54 - Non-Hispanic White    78  14,165,493
7 Male - Age 55 – 64 - Non-Hispanic White    61   9,215,914
8 Male - Age 65 or older - Non-Hispanic White    47  11,755,768
9 Male - Non-Hispanic Other    33   4,146,032
10 Female - Hispanic (Any Race)    43  10,625,145
11 Female - Age 18 – 44 - Non-Hispanic Black    39   7,307,267
12 Female - Age 45 or older - Non-Hispanic Black    33   5,144,462
13 Female - Age 18 – 24 - Non-Hispanic White    32   8,531,226
14 Female - Age 25 – 34 - Non-Hispanic White    58  12,373,489
15 Female - Age 35 – 44 - Non-Hispanic White   102  16,061,583
16 Female - Age 45 – 54 - Non-Hispanic White    92  14,513,973
17 Female - Age 55 – 64 - Non-Hispanic White    70   9,837,412
18 Female - Age 65 or older - Non-Hispanic White    93  15,762,147
19 Female - Non-Hispanic Other    21   4,762,691
N/A Missing Demographic Information    31     N/A    
TOTAL 1,083 200,706,700

Data Collection Schedule

The survey was conducted over a ten-day period, from October 05 through October 15. A total of 1,083 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 in calculating an overall CASRO response rate of approximately 48.98 percent.

Table 4: Distribution of Household Cases by Disposition

Disposition Category Number of Households
Telephone Numbers Available 4,737
Telephone Numbers Released 3,190
Telephone Numbers Not Dialed     0
Telephone Numbers Dialed 3,190
Out-of-Scope Numbers (Ineligible)   830
BG - Business   211
CF - Computer/Fax   230
DS - Disconnected number   335
NC - Number change    23
NQ - No one 18 years old or older in household    12
UNB - Unavailable before and during study period    19
Scope Undetermined   485
NA - No answer   247
BZ - Busy     1
AM - Answering machine    44
LM - Left message     5
CCC - Cannot complete call     0
PM - Privacy manager    12
NQL - Eligibility undetermined because of language problems or deafness    23
RFI - Refused to speak with interviewer (screening incomplete)    17
HRI - Hard refusal *   126
OD - Maximum call attempts reached     0
CBU - Callback undetermined    10
CSU - Callback Spanish undetermined     0
In-Scope Numbers 1,875
Complete 1,083
Partial complete     4
DIP - Reinterview deletion, ineligible person in household interviewed     3
DDA - Reinterview deletion, discrepancy in answers during reinterview     0
CB - Callback   128
CBS - Callback Spanish     0
NAQ - No answer qualified   362
BZQ - Busy qualified     0
AMQ - Answering machine qualified   117
LMQ - Left message qualified    11
CCQ - Cannot complete call qualified     2
PMQ - Privacy manager qualified     3
DL - Deaf/Language    39
RFQ - Respondent refusal    13
UN - Unavailable    28
DR - Respondent deceased prior to completion of interview     0
AC - The area code is changed but not the number     0
HRQ - Hard refusal *    82
CASRO Response Rate 48.98%