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Omnibus Survey Household Survey Month Specific Information September 2002

Omnibus Survey
Household Survey
Month Specific Information
September 2002

This report presents the results of the September 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 September 2002 survey collected data from September 07, 2002 through September 16, 2002. Data were collected from households in the U.S. using a Random-Digit-Dialed telephone methodology. The final completed sample size is 1,034 cases, and the total number of variables in the public-use dataset is 148. The data were collected by M. Davis and Company, under contract with the BTS.

Sample Telephone Number Selection

There were 8,200 telephone numbers for the September 2002 survey. A total of 5,188 of these numbers were identified as working residential numbers and were divided into 104 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 September’s sample were used to conduct a pretest. Each pretest replicate had approximately 50 households. Forty (40) of the 104 September replicates were not utilized in the actual interviewing, resulting in 3,193 numbers being released for use by the telephone interviewers. For this survey, the total number of telephone numbers in the sampling frame, N, is 261,905,600. The total number of telephone numbers in the sample (numbers dialed) is 3,193.

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 1.159
Standard deviation 0.482
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 1.982
Standard deviation 0.827
Minimum     1
25th percentile     1
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)    42  10,167,034
2 Male - Non-Hispanic Black    28   9,883,467
3 Male - Age 18 – 24 - Non-Hispanic White    17   8,635,241
4 Male - Age 25 – 34 - Non-Hispanic White    54  11,985,017
5 Male - Age 35 – 44 - Non-Hispanic White    73  15,833,339
6 Male - Age 45 – 54 - Non-Hispanic White    59  14,165,493
7 Male - Age 55 – 64 - Non-Hispanic White    48   9,215,914
8 Male - Age 65 or older - Non-Hispanic White    58  11,755,768
9 Male - Non-Hispanic Other    16   4,146,032
10 Female - Hispanic (Any Race)    83  10,625,145
11 Female - Age 18 – 44 - Non-Hispanic Black    34   7,307,267
12 Female - Age 45 or older - Non-Hispanic Black    26   5,144,462
13 Female - Age 18 – 24 - Non-Hispanic White    30   8,531,226
14 Female - Age 25 – 34 - Non-Hispanic White    63  12,373,489
15 Female - Age 35 – 44 - Non-Hispanic White    88  16,061,583
16 Female - Age 45 – 54 - Non-Hispanic White   106  14,513,973
17 Female - Age 55 – 64 - Non-Hispanic White    67   9,837,412
18 Female - Age 65 or older - Non-Hispanic White    86  15,762,147
19 Female - Non-Hispanic Other    28   4,762,691
N/A Missing Demographic Information    28     N/A    
TOTAL 1,034 200,706,700

Data Collection Schedule

The survey was conducted over a ten-day period, from September 07 through September 16. A total of 1,034 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 47 percent.

Table 4: Distribution of Household Cases by Disposition

Disposition Category Number of Households
Telephone Numbers Available 4,788
Telephone Numbers Released 3,193
Telephone Numbers Not Dialed     0
Telephone Numbers Dialed 3,193
Out-of-Scope Numbers (Ineligible)   855
BG - Business   182
CF - Computer/Fax   268
DS - Disconnected number   360
NC - Number change    23
NQ - No one 18 years old or older in household    11
UNB - Unavailable before and during study period    11
Scope Undetermined   392
NA - No answer   271
BZ - Busy     0
AM - Answering machine    64
LM - Left message    23
CCC - Cannot complete call     1
PM - Privacy manager    18
NQL - Eligibility undetermined because of language problems or deafness     6
RFI - Refused to speak with interviewer (screening incomplete)     2
HRI - Initial Refusal - Requested name be removed from calling list     7
OD - Maximum call attempts reached     0
CBU - Callback undetermined     0
CSU - Callback Spanish undetermined     0
In-Scope Numbers 1,946
Complete 1,034
Partial complete     8
DIP - Reinterview deletion, ineligible person in household interviewed     3
DDA - Reinterview deletion, discrepancy in answers during reinterview     2
CB - Callback   199
CBS - Callback Spanish     0
NAQ - No answer qualified   269
BZQ - Busy qualified     0
AMQ - Answering machine qualified   137
LMQ - Left message qualified    14
CCQ - Cannot complete call qualified     3
PMQ - Privacy manager qualified     0
DL - Deaf/Language    64
RFQ - Respondent refusal    39
UN - Unavailable    42
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   121
CASRO Response Rate 47.20%