8\. SURVEY FIELD RESULTS

This chapter presents the field results of the 2001 National Survey of
Veterans (NSV 2001) data collection effort. We first examine the final
sample yields and response rates of completed interviews against the
sample design targets. Next, we detail the call results for each type of
instrument and sample. We also present analyses of selected operating
statistics such as location and cooperation rates.

# 8.1 Completed Interviews

The NSV 2001 had sample targets of 13,000 completed extended interviews
from the household screening of RDD telephone numbers and 7,000
completed extended interviews from the List Sample, for a total of
20,000 completed extended interviews. Overall, we achieved 100.2 percent
of that target. For the RDD sample, we achieved 99.7 percent of the
target and for the List Sample, we achieved 101.3 percent of the target.

# 8.2 Completed Interviews by Sample Stratum

####  List Sample

The NSV 2001 sample design set interview completion targets by sample
stratum for both the List and RDD Samples. The main objective of the
List Sample stratification was to augment the sample with veterans in
the mandatory health care enrollment priority groups (groups 1 through
6), and with female veterans. The List Sample target for the female
veterans was 581 completed extended interviews, and we achieved 99.1
percent of that target (576 completed interviews with female veterans).
The List Sample targets for African American and Hispanic veterans were
574 and 280, respectively. We completed 897 extended interviews with
African American veterans, and 344 extended interviews with Hispanic
veterans. Thus, we almost met the target for female veterans and
exceeded the targets for African American and Hispanic veterans. We
attribute the higher than expected number of completed extended
interviews for these two groups to the fact that the list frame
contained a higher proportion of these minority groups than exists in
the veteran population, and the latter rate is what we had assumed for
sample design purposes.

We also compared the target and achieved List Sample completed extended
interviews by priority groups (Table 8-1). PRIOADJ3 represents the
priority group as it appeared on the list frame.

Table 8-1. Target versus achieved List Sample completed extended
interviews by priority group (PRIOADJ3)

  --------------- ------------------ ------------------ ------------------
  PRIOADJ3        Target             Achieved           Percent of Target

  1               1,239              1,410              113.8

  2               1,200              1,354              112.8

  3               1,636              1,758              107.5

  4               931                549                59.0

  5               1,231              1,179              95.8

  6               763                842                110.4

  TOTAL LIST      7,000              7,092              101.3
  --------------- ------------------ ------------------ ------------------

We exceeded the target for four out of the six mandatory priority
groups. The two groups where we fell short were priority group 5, for
which we achieved almost 96 percent of the target, and priority group 4,
for which we achieved only 59 percent of the target. It turns out that
we underestimated the proportion of priority group 4 veterans that would
be ineligible for the survey because they were institutionalized or
deceased. The proportion ineligible among the priority group 4 veterans
was 30.9 percent, whereas less than 5 percent of veterans in priority
groups 2, 3 and 6 were ineligible, and just over 7 percent of priority
groups 1 and 5 veterans were ineligible (see Table 8-4).

The target List Sample counts by priority group were derived from the
list frame variable, PRIOADJ3. Information on the List frame was for a
particular point in time. It is possible that by the time we interviewed
the veteran this information had changed, thus putting that veteran in a
different priority group. Table 8-2 gives the cross-tabulation of the
priority group as it appeared on the list frame (PRIOADJ3) and that
determined from survey responses (Observed Priority). Based on the
survey responses, the number of completed extended interviews for
priority group 4 veterans was much smaller than expected based on the
number of priority group 4 veterans on the list frame. In fact, many
veterans recorded on the list frame as belonging to priority group 4
turned out to be priority group 5 veterans. As a result, only 81 of the
List Sample eligible respondents who were priority group 4 veterans on
the list frame were actually categorized as belonging to priority group
4 on the basis of their survey responses. At the same time, a large
number of veterans recorded on the List frame as priority group 5 or
priority group 6 turned out to belong to other priority groups. From
priority group 5, 253 veterans were observed to belong to priority group
7. From priority group 6, 419 veterans gave survey responses that
categorized them as belonging to priority groups 3, 5 or 7.

Table 8-2. List priority (PRIOADJ3) by observed priority

  ----------- ---------- ------- ------- ------- ------- ------- ------- --------
  PRIOADJ3    Observed                                                   
              Priority                                                   

              1          2       3       4       5       6       7\*     ALL

  1           1,308      28      14      1       16      16      27      1,410

  2           85         1,105   54      4       36      16      54      1,354

  3           23         65      1,475   1       61      34      99      1,758

  4           13         6       10      94      345     8       73      549

  5           7          4       15      4       839     51      259     1,179

  6           14         23      72      1       194     395     143     842

  TOTAL LIST  1,450      1,231   1,640   105     1,491   520     655     7,092
  ----------- ---------- ------- ------- ------- ------- ------- ------- --------

\* 113 cases with unknown "Observed Priority" have been combined with
priority 7.

We did not ask questions about catastrophically disabled veterans on the
survey. These veterans fall into priority group 4. Pensioners receiving
aid and attendance were classified into either priority group 4 or
priority group 5. Priority group 6 veterans on the List sampling frame
were those enrolled for VA health care who were coming or planning to
come to the VA solely for treatment for disorders associated with
exposure to a toxic substance, radiation, or for disorders associated
with service in the Persian Gulf. Veterans who did not meet the criteria
for priority groups 1 through 5 and indicated exposure (regardless of
whether they were presently enrolled for this type of care) were
classified into priority group 6. Priority group 6 also included
compensated veterans with a zero percent rating who did not meet the
criteria for priority groups 1 through 5.

####  RDD Sample

We made assumptions about the distribution of the veteran population
across various subgroups, and used those assumptions to arrive at our
sample design targets for each subgroup. Because of sampling
variability, we expected the observed yields to differ somewhat from
those targets, even if our assumptions were correct. However, since the
observed yields depended on the actual (not assumed) distributions of
the veteran population across subgroups, the difference could be larger.

We set an RDD Sample target of 662 completed extended interviews with
female veterans, and actually completed 699 interviews (105.6 percent of
the target). The targets for African American and Hispanic veterans were
1,066 and 520 completed extended interviews, respectively. We completed
983 extended interviews with African American veterans (92.2 percent of
the target), and 558 extended interviews with Hispanic veterans (107.3
percent of the target) .

Table 8-3 shows that, while we met the overall target for the RDD
Sample, there was considerable variability among the individual priority
groups. According to the veteran population distribution used for the
NSV 2001 sample design (see Chapter 3), the two smallest priority groups
were groups 4 and 6. However, the number of veterans in priority group 4
turned out to be only a fraction (17.4 percent) of what we projected
from our assumed distribution. On the other hand, the number of veterans
belonging to priority group 6 was 41 times what we expected. This could
be partially due to the fact that the absolute numbers for the RDD
targets for priority groups 4 and 6 were also very low, which led to
large percentage differences. Also, for Priority 6 the definition for
the target population was slightly different than what was used to count
the achieved number. Data used to estimate the target population was
only available for veterans using VA facilities solely for treatment of
environmental exposures, whereas the observed population considered
anyone stating they had been exposed to environmental hazards regardless
of treatment. The RDD Sample completed extended interviews for priority
group 5 also fell significantly short, at just over 70 percent of the
target.

Table 8-3. Target versus achieved RDD Sample completed extended
interviews by priority group

  --------------- ------------------ ------------------ ------------------
  Observed        Target             Achieved           Percent of Target
  Priority                                              

  1               295                371                125.8

  2               271                300                110.7

  3               661                741                112.1

  4               69                 12                 17.4

  5               3,731              2,636              70.7

  6               36                 1,479              4,108.3

  7\*             7,937              7,417              93.4

  TOTAL RDD       13,000             12,956             99.7
  --------------- ------------------ ------------------ ------------------

\* 61 cases with unknown "Observed Priority" have been combined with
priority 7.

# 

# 8.3 List Sample Extended Interview Results and Response Rates

For the NSV 2001 List Sample, we attempted to complete extended
interviews with a total of 13,129 individuals. With 7,092 of these, we
were successful in our attempts. Of the remaining cases, we determined
that 1,151 were out of scope, principally because they were deceased or
institutionalized, and 427 were, for a variety of reasons, eligible
nonrespondents. We could not determine the eligibility of 4,459 cases,
mainly because the veterans could not be located.

As described in Chapter 6, we divided sample cases into four eligibility
and response categories -- eligible respondents, ineligible (out of
scope), eligible nonrespondents, and eligibility unknown. Table 8-4
shows these response status categories for the six priority groups, as
represented by the list frame variable PRIOADJ3. The proportion of
eligible respondents was much lower for priority group 4 veterans as
compared to the other priority groups. This was due to the large
proportion of priority group 4 veterans that were ineligible (out of
scope) for the survey. The proportion of eligible nonrespondent veterans
was roughly the same across all priority groups except priority group 6,
for which that proportion was slightly lower.

Table 8-4. Response status by priority group (List Sample)

  -------------- -------------- --------------- -------------- --------------
  PRIOADJ3       Eligible\      Eligible\       Ineligible     Eligibility\
                 Respondent     Nonrespondent                  Unknown

  1              60.7           3.8             7.1            28.4

  2              60.1           3.4             4.3            32.2

  3              57.3           3.0             3.9            35.8

  4              31.4           3.0             30.9           34.7

  5              51.1           3.4             7.4            38.1

  6              58.9           2.7             4.1            34.3

  TOTAL LIST     54.0           3.2             8.8            34.0
  -------------- -------------- --------------- -------------- --------------

Table 8-5 shows telephone interviewing results by age group (less than
50, 50 to 64, and over 64). The proportion of ineligible persons
increased monotonically with age because the incidence of
institutionalized and deceased persons increases with age. On the other
hand, the proportion of eligibility unknown respondents decreased
monotonically with age because it is more difficult to locate younger

Table 8-5. Response status by age group (List Sample)

+-------------+-------------+-------------+-------------+-------------+
| Age Group   | Eligible\   | Eligible\   | Ineligible  | E           |
|             | Respondent  | No          |             | ligibility\ |
|             |             | nrespondent |             | Unknown     |
+-------------+-------------+-------------+-------------+-------------+
| > Less than | 48.0        | 2.9         | 1.9         | 47.2        |
| > 50        |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| > 50-64     | 59.5        | 2.6         | 4.0         | 33.9        |
+-------------+-------------+-------------+-------------+-------------+
| > Over 64   | 53.7        | 3.9         | 16.7        | 25.7        |
+-------------+-------------+-------------+-------------+-------------+
| > TOTAL     | 54.0        | 3.2         | 8.8         | 34.0        |
| > LIST      |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+

veterans. The proportion of eligible nonrespondents was slightly higher
for elderly veterans (over 64 years) mainly because these persons were
more likely to be too incapacitated to respond to the survey. For the
same reason that younger veterans (less than 50 years) were more likely
to fall into the eligibility unknown category, a lower proportion of
them were eligible respondents.

Table 8-6 gives the distribution of response status for male and female
veterans. The proportion of ineligible male veterans was almost twice
that of female veterans, mainly because males are more likely to be
institutionalized or deceased. On the other hand, the proportion of
eligibility unknown respondents was higher for female veterans because
we had less information with which to locate them. As a result, the
proportion of eligible female veteran respondents was slightly lower
than that of male veterans.

Table 8-6. Response status by gender (List Sample)

+-------------+-------------+-------------+-------------+-------------+
| Gender      | Eligible\   | Eligible\   | Ineligible  | E           |
|             | Respondent  | No          |             | ligibility\ |
|             |             | nrespondent |             | Unknown     |
+-------------+-------------+-------------+-------------+-------------+
| > Male      | 54.1        | 3.3         | 9.1         | 33.5        |
+-------------+-------------+-------------+-------------+-------------+
| > Female    | 52.8        | 3.2         | 4.8         | 39.2        |
+-------------+-------------+-------------+-------------+-------------+
| > TOTAL     | 54.0        | 3.2         | 8.8         | 34.0        |
| > LIST      |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+

Table 8-7 shows the List Sample veteran response status distributed
across census regions. The proportion of eligibility unknown respondents
in the Midwest region was slightly lower and the proportion of eligible
respondents slightly higher than those in the other three regions. The
proportion of ineligible persons was slightly lower in the West,
although the proportion of eligible nonrespondents was almost the same
in that region as in all others.

Table 8-7. Response status by census region (List Sample)

+-------------+-------------+-------------+-------------+-------------+
| Census      | Eligible\   | Eligible\   | Ineligible  | E           |
| Region      | Respondent  | No          |             | ligibility\ |
|             |             | nrespondent |             | Unknown     |
+-------------+-------------+-------------+-------------+-------------+
| > Northeast | 51.6        | 3.0         | 10.5        | 34.9        |
+-------------+-------------+-------------+-------------+-------------+
| > Midwest   | 56.8        | 3.6         | 9.7         | 29.9        |
+-------------+-------------+-------------+-------------+-------------+
| > South     | 54.1        | 3.2         | 8.6         | 34.1        |
+-------------+-------------+-------------+-------------+-------------+
| > West      | 53.0        | 3.2         | 6.8         | 37.0        |
+-------------+-------------+-------------+-------------+-------------+
| > TOTAL     | 54.0        | 3.2         | 8.8         | 34.0        |
| > LIST      |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+

# 8.4 RDD Household Screening Results and Response Rates

As discussed in Chapter 6, the RDD Sample screening criteria was
somewhat loose. Since we asked one household member to report military
service for all other household members, we knew that some screener
respondents would not have enough knowledge to provide definitive
information for determining veteran status. Therefore, we asked detailed
military service questions of all potential veterans (or their
knowledgeable proxies) identified and selected for an extended interview
through the screening process. The results of this approach are shown in
Tables 8-8 and 8-9. A total of 305,500 telephone numbers were sampled
for the RDD Sample. Of these, 300,000 were sampled from the 50 states
and District of Columbia using a list-assisted random digit dialing
method (national RDD Sample) and 5,500 were sampled from Puerto Rico
using a naïve RDD sampling method (Puerto Rico RDD Sample).

Of the 300,000 telephone numbers sampled for the national sample,
205,949 were dialed. We did not call the remaining 94,051 numbers
because we had identified them as nonworking or business numbers before
data collection began. Table 8-8 shows the household level screening
interview response status for the 205,949 list-assisted RDD Sample
telephone numbers and the 5,500 Puerto Rico RDD Sample telephone numbers
for which calls were attempted. As discussed in Chapter 6, there were no
households with a response status of eligible nonrespondent because, by
definition, a completed screening interview can be categorized as
eligible or ineligible. Hence, we were able to assign an eligible or
ineligible status to all completed screening interviews. If the
household did not complete a screening

Table 8-8. Household screener interview results by sample type

+-----------------+-----------------+-----------------+-----------------+
| Sample Type     | Eligible        | Ineligible      | Eligibility     |
|                 | Respondents     |                 | Unknown         |
+-----------------+-----------------+-----------------+-----------------+
| > RDD National  | 18,810          | 116,212         | 70,927          |
+-----------------+-----------------+-----------------+-----------------+
| > RDD Puerto    | 96              | 4,137           | 1,267           |
| > Rico          |                 |                 |                 |
+-----------------+-----------------+-----------------+-----------------+
| > TOTAL RDD     | 18,906          | 120,349         | 72,194          |
+-----------------+-----------------+-----------------+-----------------+

interview, then we assigned the response status eligibility unknown. The
RDD screener response rate was 67.6 percent.[^1]

We identified 18,906 RDD Sample households (national and Puerto Rico) as
containing potential veterans and 120,349 as ineligible. We could not
determine eligibility for the remaining 72,194 numbers. Of the 120,349
ineligible telephone numbers, 54,304 were residential telephone numbers
(i.e., telephones for households with no veterans in them), and the rest
were either business or nonworking telephone numbers. Thus, a total of
73,210 telephone households were identified during RDD screening and
18,906 had at least one potential veteran.

Table 8-9 shows the comparative results of the household screening
process, in terms of the yield of households with potential veterans. Of
all households screened, 25.8 percent (18,906) had at least one
potential veteran. Because of the deliberately relaxed criteria for
identifying potential veterans at this stage of the screening, the
proportion of households with a potential veteran found during our
screening process was higher than the proportion determined by the
extended interview (22.1 percent). The assumption we made for the
purpose of the sample design was that one out of every four households
would be a veteran household (see Chapter 3).

Table 8-9. Distribution of telephone households by number of potential
veterans in the household

  --------- ------------ ------------ ------------ ------------ ------------
            Households                                          All
            with number                                         Households
            of Veterans                                         
            in the                                              
            Household                                           
            equal to                                            

            0            1            2            3 or more    

  Count     54,304       17,936       909          61           73,210

  Percent   74.2         24.5         1.2          0.1          100.0
  --------- ------------ ------------ ------------ ------------ ------------

Table 8-9 also shows that 17,936 of the 18,906 veteran households (94.9
percent) had one potential veteran, while 4.8 percent of the veteran
households contained two potential veterans. Only 61 households (0.3
percent of the veteran households) had more than two potential veterans.

# 8.5 RDD Sample Extended Interview Results and Response Rates

From the 18,906 RDD Sample screened household with potential veterans,
we identified 19,950 potential veterans. Nearly two-thirds of these
(12,956 out of 19,950 or 64.9 percent) completed the extended interview.
Only 3.1 percent were eligible nonrespondents and 11.5 percent were out
of scope (ineligible) for the survey because they were not actually
veterans. The proportion with eligibility unknown was 20.5 percent.

The RDD Sample extended interview response rate, at 76.4 percent, was
better than that for the List Sample (62.8 percent).[^2] In part this is
because a relatively higher proportion of List Sample veterans could not
be located, which also meant they could not be contacted. The overall
RDD Sample (screener and extended interview) response rate was 51.6
percent.[^3] Of the RDD Sample respondents, 64.9 percent were eligible
veterans who completed the interview and 11.5 percent responded to the
extended interview eligibility questions but were determined not to be
veterans. Of the List Sample respondents, 54.0 percent were eligible
veterans who completed the interview and 8.8 percent were determined not
to be eligible. We could not determine eligibility for 20.5 percent of
the screened RDD Sample cases or for 34.0 percent of the List Sample
cases. The main reason for the higher proportion of List Sample cases
with unknown eligibility was, again, our inability to locate them. This
was not an issue for RDD Sample cases because contact was made during
the household screening interview. There were no notable differences in
the proportion of eligible nonrespondents between the RDD and List
Samples (3.1 percent for the RDD Sample versus 3.2 percent for the List
Sample). In the following sections, we compare the distributions of
response status categories across age groups (Table 8-10), gender (Table
8‑11) and census regions (Table 8-12).

Table 8-10. Distribution of response status by age groups (RDD Sample)

+-------------+-------------+-------------+-------------+-------------+
| Age Group   | Eligible\   | Eligible\   | Ineligible  | E           |
|             | Respondent  | No          |             | ligibility\ |
|             |             | nrespondent |             | Unknown     |
+-------------+-------------+-------------+-------------+-------------+
| > Less than | 59.1        | 2.9         | 17.0        | 21.0        |
| > 50        |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| > 50-64     | 63.6        | 2.6         | 12.3        | 21.5        |
+-------------+-------------+-------------+-------------+-------------+
| > Over 64   | 70.9        | 3.7         | 6.5         | 18.9        |
+-------------+-------------+-------------+-------------+-------------+
| > TOTAL RDD | 64.9        | 3.1         | 11.5        | 20.5        |
+-------------+-------------+-------------+-------------+-------------+

Table 8-11. Distribution of response status by gender (RDD Sample)

+-------------+-------------+-------------+-------------+-------------+
| Gender      | Eligible\   | Eligible\   | Ineligible  | E           |
|             | Respondent  | No          |             | ligibility\ |
|             |             | nrespondent |             | Unknown     |
+-------------+-------------+-------------+-------------+-------------+
| > Male      | 65.4        | 3.1         | 11.0        | 20.5        |
+-------------+-------------+-------------+-------------+-------------+
| > Female    | 58.1        | 2.8         | 19.6        | 19.5        |
+-------------+-------------+-------------+-------------+-------------+
| > TOTAL RDD | 64.9        | 3.1         | 11.5        | 20.5        |
+-------------+-------------+-------------+-------------+-------------+

Table 8-12. Distribution of response status by census region (RDD
Sample)

+-------------+-------------+-------------+-------------+-------------+
| Census      | Eligible\   | Eligible\   | Ineligible  | E           |
| Region      | Respondent  | No          |             | ligibility\ |
|             |             | nrespondent |             | Unknown     |
+-------------+-------------+-------------+-------------+-------------+
| > Northeast | 64.7        | 3.5         | 11.8        | 20.0        |
+-------------+-------------+-------------+-------------+-------------+
| > Midwest   | 65.6        | 2.9         | 11.5        | 20.0        |
+-------------+-------------+-------------+-------------+-------------+
| > South     | 63.7        | 3.1         | 11.9        | 21.3        |
+-------------+-------------+-------------+-------------+-------------+
| > West      | 66.7        | 2.7         | 10.8        | 19.8        |
+-------------+-------------+-------------+-------------+-------------+
| > TOTAL RDD | 64.9        | 3.1         | 11.5        | 20.5        |
+-------------+-------------+-------------+-------------+-------------+

Table 8-10 shows that the ineligibility rate decreased monotonically
with age. That is, the proportion of potential veterans identified
during the screening interview that were not actually veterans decreased
with age. The proportion of elderly veterans (over 64) that did not
respond to the extended interview was also higher than in the other two
age groups.

The ineligibility rate was also higher for potential female veterans
(Table 8-11). Household members tended to be more uncertain about
identifying potential female veterans during the screening interview
than they were about identifying potential male veterans. There was no
significant difference in the distribution of response status across
census regions (Table 8-12).

# 8.6 List Sample Location Rates

We located 73.6 percent of List Sample veterans. By definition, location
rates for the response categories eligible respondent, ineligible and
eligible nonrespondents were 100 percent. The location rate for veterans
of unknown eligibility was 22.2 percent. Although we located these
veterans, we assigned them to the eligibility unknown category because
they did not provide the information necessary to determine their
eligibility. Table 8-13 gives the location rate by three age groups
(less than 50, 50 to 64, over 64). We found it more difficult to locate
younger veterans than older ones, perhaps because younger people in
general tend to be more mobile or less likely to have a telephone or
address listing in their name.

Table 8-13. List Sample location rates by age group

+-----------------------+----------------------------------------------+
| Age Group             | Location Rate (Percent)                      |
+-----------------------+----------------------------------------------+
| > Less than 50        | 58.6                                         |
+-----------------------+----------------------------------------------+
| > 50-64               | 72.5                                         |
+-----------------------+----------------------------------------------+
| > Over 64             | 83.9                                         |
+-----------------------+----------------------------------------------+
| > TOTAL LIST          | 73.6                                         |
+-----------------------+----------------------------------------------+

The location rate was also higher for male veterans than for female
veterans (74.3 percent for male veterans versus 66.1 percent for female
veterans). We may have had difficulty locating female veterans because
they are less likely to have a telephone or address listing in their own
or maiden names.

Table 8-14 gives the List Sample location rates by census region. Our
location rate was highest in the Midwest region and somewhat lower in
the West.

Table 8-14. List Sample location rates by census region

+--------------------------+-------------------------------------------+
| Census Region            | Location Rate (Percent)                   |
+--------------------------+-------------------------------------------+
| > Northeast              | 74.1                                      |
+--------------------------+-------------------------------------------+
| > Midwest                | 77.4                                      |
+--------------------------+-------------------------------------------+
| > South                  | 73.6                                      |
+--------------------------+-------------------------------------------+
| > West                   | 69.7                                      |
+--------------------------+-------------------------------------------+
| > TOTAL LIST             | 73.6                                      |
+--------------------------+-------------------------------------------+

#  8.7 Cooperation Rates

Survey cooperation rates are one indicator of interviewers' ability to
complete an interview after contact has been established with sampled
individuals. They also demonstrate the effectiveness of interviewer
training. The calculation for cooperation rates uses completed
interviews and refusals only. Included with the completed interview
cases are all ineligible (out-of-scope) cases (as determined by
completion of the required screening questions ). We calculated
cooperation at two stages: at the initial attempt to complete an
interview and after making all attempts to persuade those who initially
refused to participate in the survey (refusal conversion). Table 8-15
shows the number of initial refusal cases, number of refusal conversion
cases, and the refusal conversion rates by sample type. One-third of
initial refusals at the RDD Sample screening interview were converted to
completed interviews while more than 80 percent of initial refusals at
the RDD and List Sample extended interview level were converted.

Table 8-15. Refusal conversion rates by sample type

+----------------+-----------------+-----------------+-----------------+
| Sample Type    | Initial         | Refusal         | Refusal         |
|                | Refusals        | Conversions     | Conversion Rate |
+----------------+-----------------+-----------------+-----------------+
| > RDD Screener | 54,781          | 18,072          | 33.0            |
+----------------+-----------------+-----------------+-----------------+
| > RDD Extended | 1,935           | 1,566           | 80.9            |
+----------------+-----------------+-----------------+-----------------+
| > List         | 983             | 807             | 82.1            |
| > Extended     |                 |                 |                 |
+----------------+-----------------+-----------------+-----------------+

Table 8-16 presents the initial cooperation rates, the conversion rates
for those who initially refused, and the net cooperation rates after
both stages for the RDD Sample screening interview, and RDD and List
Sample extended interview. The percentages are based only on those cases
for which a telephone interview was attempted.

Table 8-16. Cooperation rate by sample type

+-----------------+-----------------+-----------------+-----------------+
| Sample Type     | Initial\        | Refusal\        | Final\          |
|                 | Cooperation     | Conversion Rate | Cooperation     |
|                 | Rate            |                 | Rate            |
+-----------------+-----------------+-----------------+-----------------+
| > RDD Screener  | 50.1            | 33.0            | 66.5            |
+-----------------+-----------------+-----------------+-----------------+
| > RDD Extended  | 86.5            | 80.9            | 96.4            |
+-----------------+-----------------+-----------------+-----------------+
| > List Extended | 85.8            | 82.1            | 95.1            |
+-----------------+-----------------+-----------------+-----------------+

The RDD screening interview had an initial cooperation rate of 50.1
percent, a conversion rate of 33.0 percent and a net cooperation rate of
66.5 percent. Among individuals selected for the RDD extended interview,
the initial cooperation rate was 86.5 percent, the conversion rate was
80.9 percent, and the net cooperation rate was 96.4 percent.

The List Sample veterans' initial cooperation rate, at 85.8 percent, was
slightly lower than that of the RDD Sample. On the other hand, the List
Sample extended interview refusal conversion rate of 82.1 percent was
slightly higher than the RDD Sample rate. The List Sample net
cooperation rate (95.1 percent) for the extended interview was slightly
lower than the RDD Sample extended interview net cooperation rate (96.4
percent).

# 8.8 Questionnaire Administration Timing

Table 8-17 presents selected statistics about the amount of time it took
veterans to complete the screening and extended interviews. The average
and median administration times for the RDD screening interview were 4.1
and 3.8 minutes, respectively. The average administration time is higher
than the median time because the distribution is skewed to the right.
List Sample veterans took an average of 38.7 minutes to complete the
extended interview, while the RDD Sample took 33.3 minutes. It is not
surprising that List Sample veterans took longer, since they generally
have more medical conditions and medical treatment experiences to
report, and those sections of the interview were the most time-consuming
to complete. Table 8-17 also shows that the median time for the List
Sample extended interviews was 36.1 minutes as compared with 31.3
minutes for the RDD Sample extended interviews.

Table 8-17. Questionnaire administration time in minutes by sample type

  --------------- ----------- --------- ---------- --------- ---------- ---------
  Sample Type     Number      Mean      Lower      Median    Upper      Maximum
                  Completed             Quartile             Quartile   

  RDD Screener    18,906      4.1       3.3        3.8       4.5        27.2

  RDD Extended    12,956      33.3      26.6       31.3      37.6       136.5

  List Extended   7,092       38.7      30.7       36.1      43.8       137.6
  --------------- ----------- --------- ---------- --------- ---------- ---------

The upper and lower quartile values of interview administration time and
the maximum value are also shown in Table 8-17 for the RDD screener, RDD
and List Sample extended interviews. Seventy five percent of the RDD
screener interviews were completed in less than four-and-half minutes.
While 75 percent of the RDD extended interviews were completed in less
than 38 minutes, the comparable figure for the List Sample extended
interviews was almost three-quarters of an hour. Although a few extended
interviews took over two hours, 95 percent of the extended interviews
took under 52 minutes for the RDD Sample and just over an hour for the
List Sample. Overall (both RDD and List Sample cases), 654 extended
interviews took more than an hour. The NSV 2001 cooperation rates in
themselves are testimony to the sampled veterans' support of the survey
effort. The fact that 654 veterans were willing to devote over an hour
of their time to the interview further substantiates that support.

# 8.9 Telephone Call Statistics

Table 8-18 presents dialing statistics for completed interviews. It
shows, for each sample type, how many calls had to be made to complete
an interview. Overall, just over 30 percent of the RDD screener cases
were completed in one call and almost half of these cases were completed
in two calls. More than 95 percent of the RDD screener cases were
completed within 12 calls. The average number of calls per screened
household was 3.9 calls.

Over 48 percent of the RDD extended interviews were completed in one
call and just over 23 percent of the List Sample extended interviews
were completed in one call. Almost 62 percent of extended interviews
were completed within 2 calls for the RDD Sample, and just over 40
percent of List Sample extended interviews were completed within 2
calls. When the count rises to 3 calls, there was still a significant
difference in the proportion of completed extended interviews by sample
type, at 70 percent for the RDD Sample and 53 percent for the List
Sample. After five calls, the completion rates for the RDD and List
Sample cases were 80 percent and 71 percent, respectively. The average
number of calls per completed extended interview was 3.6 for the RDD
Sample and 4.9 for the List Sample. It took fewer calls to recontact the
RDD Sample cases, for which contact had already been established at the
screening interview stage, than the List Sample cases, where the
extended interview was our first contact. For the combined RDD and List
Samples, 91 percent of the extended interviews were completed within 10
calls, 94 percent within 12 calls, and 96 percent within 14 calls.

Table 8-18. Number of completed cases by number of calls for each sample
type

  ------------ ---------- --------- ---------- --------- ---------- ---------
  Number of    Sample                                               
  Call         Type                                                 

               RDD                  RDD                  List       
               Screener             Extended             Extended   

               Number     Percent   Number     Percent   Number     Percent

  1            5,771      30.5      6,243      48.2      1,654      23.3

  2            3,609      19.1      1,734      13.4      1,201      16.9

  3            2,594      13.7      1,041      8.0       884        12.5

  4            1,727      9.1       751        5.8       731        10.3

  5            1,264      6.7       592        4.6       529        7.5

  6            870        4.6       471        3.6       353        5.0

  7            641        3.4       359        2.8       301        4.2

  8            523        2.8       291        2.2       250        3.5

  9            379        2.0       255        2.0       214        3.0

  10           303        1.6       176        1.4       141        2.0

  11           244        1.3       171        1.3       149        2.1

  12           190        1.0       140        1.1       127        1.8

  13           154        0.8       131        1.0       109        1.5

  14           116        0.6       124        1.0       79         1.1

  15 or more   521        2.8       477        3.7       370        5.2

  Total        18,906     100.0     12,956     100.0     7,092      100.0
  Completed                                                         
  ------------ ---------- --------- ---------- --------- ---------- ---------

[^1]: RDD screener response rate = (eligible respondents + ineligible
    respondents)/total dialed telephone numbers.

[^2]: Extended interview response rate = eligible respondents +
    ineligible respondents/total \[List or RDD\] Sample.

[^3]: Overall RDD Sample response rate = screener response rate \*
    extended interview response rate.