Two useful measures of the quality of data in surveys are the rate of non-response and the patterns of response of proxies. This is especially true for the NLTCS because (a) it had large numbers of extreme elderly persons for whom obtaining survey responses is known to be difficult, and (b) the survey had a longitudinal dimension meaning persons have to be tracked over time.
To evaluate these issues we provide two basic types of data. The first are the non-response rates for various sample stages in both 1982 and 1984. There are two types of non-responses to be considered. The first type are the so-called "C" type "non"-responses. Actually, this is a slight misnomer in that these people did not respond because they did not qualify for the sample. The major reasons for not qualifying were (a) death, (b) institutionalization (in 1982 only), and (c) movement out of the sample area. Thus, this type of failure to respond does not represent what we typically view as non-response. The type C non-responses are described in Table 1.
|TABLE 1. Number of Ineligible Cases (Type C) by Reason and Survey Instrument Attempled, 1982 and 1984 NLTCS's|
|-||'82 Screener Telephone||'82 Screener Personal Visit||'82 Detailed Community||'84 Screener Telephone||'84 Screener Personal Visit||'84 Detailed Community||'84 Institutional Questionnaire|
|Deceased before April 1||390||340||-||537||30||-||-|
|Deceased on or after April 1||280||210||67||101||16||-||-|
|Institutionalized before April 1||1151||557||0||0||-||-||-|
|Institutionalized on or after April 1||123||161||57||-||-||-||-|
|Moved outside country before April 1||13||21||-||13||5||-||-|
|Moved outside country on or after April 1||5||6||1||-||1||1||1|
|Moved within country, beyond limit||-||81||25||16||32||19||7|
|Other Type C||72||15||14||47||6||1||-|
|In correctional facility (84 only)||-||-||-||1||-||-||-|
The second type of non-response was labelled "A" type non-response. These represent non- responses due to either failure to locate or contact persons, refusals, or failures of the proxy to be able to respond. The frequency of non-responses is described in Table 2.
|TABLE 2. Number of Nonrespondents (Type A) by Noninterview Reason and Survey Instrument Attempted, 1982 and 1984 NLTCS's|
|-||'82 Screener Personal Visit||'82 Detailed Community||'84 Screener Personal Visit||'84 Detailed Community||'84 Institutional Questionnaire||'84 Deceased Questionnaire Telephone||'84 Deceased Questionnaire Personal Visit|
|No telephone number||250||-||-||-||-||30||-|
|No answer after repeated calls||7||-||-||-||-||4||-|
|Sample person/proxy temparily absent and proxy unavailable||15||5||21||4||3||1||2|
|Sample person/proxy unable to respond and proxy unavailable||4||3||2||19||-||7||3|
|Other Type A||89||15||126||57||16||10||54|
|Unable to locate||-||1||127||5||2||-||27|
|No one home||-||-||5||7||1||-||1|
|NOTE: The '82 and '84 Screeners as well as the '84 deceased questionnaire provided for both telephone and personal visit noninterview reasons. In nonrespondent cases where a reason is given in both categories, the personal visit reason was selected for tabulation.|
We can see that the frequency of non-response was very low producing response rates that are extremely high, both for the screening and detailed interview stages, in both 1982 and 1984. The response rates average about 96%. Thus, neither the longitudinal nature of the survey nor the high proportion of the extreme elderly seems to have caused problems in the level of response to the survey.
The second aspect of the response question is the pattern of proxy respondents. This is indicated in Table 3 where, for both 1982 and 1984, and for different levels of disability, we provide the number of responses (a) totally by sample persons, (b) totally by proxy, and (c) for combined sample person and proxy respondents.
|TABLE 3. Number of Respondents by Type, By ADL Score, and Senility Status|
|-||Non-Disabled||IADL Only||1-2 ADL||3-4 ADL||5-6 ADL||Senility|
|Sample Person Answered||418||1,234||1,360||498||252||---||3,762|
|Sample Person and Proxy Answered||41||290||264||125||176||48||763|
|Sample Person Answered||559||1,329||1,246||500||214||---||3,848|
|Sample Person and Proxy Answered||52||222||226||134||172||34||772|
As would be expected the proportion of proxy responses increases as the reported disability level of the individual increase. Furthermore, we see that about 500 persons in 1982 and 1984 had a proxy respondent due to senility. Indeed, the diagnosis of senility was derived from the proxy when the person was found incapable of responding due to cognitive impairment. Of the roughly 6,000 interviews in both years, about two-thirds were totally from sample persons. The pattern of proxy response (i.e., its increase with disability), the small number of non-responses due to proxy failure (Table 2), and the large proportion of non-proxy responses provide an indication of the appropriateness of the use of proxy responses in the survey.