Research design and methods

A full evaluation of DLA would extend to all combinations of awards and would, in addition, investigate the association between disability, care and mobility needs, and the extra costs arising from disability. Even in respect of targeting lower rate awards, it would be useful to evaluate different measures of overall disability and to carry out experimental work on the adjudication process. The time-scale for the study was short, however, and we tailored the research design accordingly, concentrating resources on the question of how successfully lower rate awards are targeting moderately disabled people with care and mobility needs.

The policy requirement was for quantitative information broadly representative of the population of disabled people applying for DLA. To assess how well the lower rates are targeted, the care and mobility needs of successful and unsuccessful applicants must be compared. A large-scale interview survey of a sample of recent DLA applicants, stratified between lower rate awards and rejected claims, was required. The survey aimed to achieve interviews with 1000 applicants who had recently been awarded at least one lower rate award and a further 500 applicants rejected solely on disability grounds, that is, whose care and mobility needs were judged to be insufficient to qualify for an award.2 Because successful applicants can receive any combination of awards, it was expected that those with a lower rate award would also include some recipients with a middle or higher rate award of the other component.

In addition, it was decided to include in the target study sample all DLA recipients who were to be interviewed as part of the separate evaluation of quality of service described in Part Two of this report. These comprised chiefly 300 recent awards at the middle or higher rate only. It was felt that boosting the number of such awards would allow wider investigation of the targeting of DLA. If overall disability and care and mobility needs increase across the boundary between unsuccessful applicants and lower rate recipients, it would be interesting to know whether the gradient continues across the lower/middle/higher rate thresholds.

A number of other considerations influenced the design for this study:

• A large sample of lower rate recipients was required because we expected that the distribution of care and mobility awards would have to be examined separately. As we have seen, DLA brings together two different benefits. Although the conditions of entitlement overlap, the care and mobility needs defined by the lower rate criteria are quite distinct. We knew from the OPCS disability surveys that these two sets of needs are unlikely to be associated (Annex 2.3). Consequently, it was necessary to ensure that sufficient numbers of both lower rate care and lower rate mobility awards were obtained so that each component could be examined

separately in relation to different areas of disability and need.

• To assess how well DLA is targeted, both type and severity of disability among lower rate recipients would have to be compared with that of unsuccessful applicants. In particular, the lower rates of DLA are intended for moderately disabled people, that is those whose disabilities correspond to OPCS severity categories 5 and 6. It was necessary then, to adapt the questionnaires developed and tested by OPCS researchers in the mid- 1980s. These schedules also provided the information to define 13 different types of disability, enabling us to evaluate the distribution of DLA more precisely than simply in relation to overall severity. We also included the

General Health Questionnaire, a screening instrument for detecting psychiatric illness, because the OPCS questionnaires gave limited coverage of mental health problems (Goldberg and Williams, 1991).

• Although overall disability is a key criterion for assessing the targeting of lower rate awards, the conditions of entitlement relate specifically to care and mobility needs, not overall severity. We therefore amended some of the OPCS questions and added others to provide fuller coverage of the conditions of entitlement for DLA. This enabled us to assess the targeting of lower rate awards against a separate, survey-based assessment of individuals' care and mobility needs.

• All age groups were sampled, including children under 16 years whose disabilities were assessed differently from those of adults aged 16 and over. However, it was decided to exclude children under the age of five. Although there is no minimum age for receiving a care award, mobility

2_{Other reasons for rejection, for example, failing to meet the prescribed qualifying periods, are not of}

awards are available only to applicants aged five or over. However, the main reason for excluding very young children was to simplify the survey process. OPCS researchers had, rightly, developed a separate questionnaire for assessing the disabilities of children under five years. It was felt that having two disability questionnaires, one for adults and one for children aged 5 to 15, plus a questionnaire for the Quality of Service studies, was quite enough for interviewers to manage.

• The research design required a sample of recent, first-time applicants because the question of targeting focused chiefly on the outcomes of new claims. It was particularly important that the information we collected about respondents' care and mobility needs reflected, as far as possible, their circumstances at the time of claiming DLA, as recorded on the application form. Sampling respondents close to the event of interest, in this case a claim for DLA, produces a `flow' sample. The main drawback is that it is not necessarily representative of previous cohorts of applicants, or the current caseload of DLA recipients.

To summarise: the design for this study focused chiefly on recent applicants whose claim for DLA resulted in a lower rate award or rejection on disability grounds. The criteria for evaluating the targeting of lower rate awards, suggested by policy makers, required replication of the methods and measures developed for the OPCS surveys of disability. In addition, information on the care and mobility needs described in the conditions of entitlement to DLA was required. Yet it is important to emphasise, as did the OPCS researchers, that the survey information we collected differs substantially from the detailed assessments of individuals' needs and circumstances typical of the adjudication of disability benefits. Our survey and the measures adopted can be used only for describing and interpreting aggregate patterns and trends across the sample as a whole, or subsamples, not for the assessment of individuals. This evaluation of the targeting of DLA awards does not test, therefore, the validity or reliability of adjudication decisions.