Biomedical Engineering Reference
In-Depth Information
of disease, but it is, instead, a multidimensional process that lasts a lifetime and involves
the physical, psychic, and social spheres of the individual:
Having a disability is not a fixed status, but rather a continually changing, evolving,
and interactive process. It is not something that one is or is not, but instead is a set of
characteristics everyone shares to varying degrees and in varying forms and combina-
tions. (Zola 1993, p. 30)
The WHODAS 2.0 (World Health Organization Disability Assessment Schedule)
(Üstün et al. 2010), as an example of a measure that adopts the ICF's conceptual frame-
work, is a psychometric questionnaire on self-perceived disability that assesses the
individual functioning in the “here” of daily life activities and “now” of the last 30 days
independently of the background disease or previous health conditions (Üstün et al.
2010, p. 5). Although disability is neither a fixed concept (i.e., aetiologically determined
by a diagnosis or immutable in time) nor dichotomous (i.e., ability and disability are
not mutually exclusive), it does not mean immeasurable: “Instead, its conception, mea-
surement, and counting differs validly with the purposes for which such numbers are
needed. The clearer the outcomes we seek, the clearer it will be what conceptions and
measurements are necessary” (Zola 1993, p. 30).
Disability is also a multidimensional construct because its measurement is multidimen-
sional. Therefore, the correct answer to the question posted in the section header is that
the elixir of measurement is found when we orient the focus of the research not just on the
theoretical definition of disability but also on the clearness of the purpose of our measure-
ments. In other words, you will just measure what you want to find. Indeed, according to
the uncertainty principle, the more precisely one property is measured (i.e., capacity), the
less precisely the other can be measured (i.e., performance). Thus, with disability being a
multiproperty object of measurement, one could not measure all of the properties at the
same time with the same tool. As a consequence, the best researcher is one who has clearly
defined the property of disability to be measured and the tool required to measure it. For all
of these reasons, an elixir of disability measurement is not even desirable. In fact, having a
variety of measuring tools and the flexibility to change measurement procedures, adapting
them to different people, contexts, and purposes, is the most reliable scientific approach.
2.1.1.1 Fitting Measure for the Purpose of the Assistive Technology Assessment
The purpose of measurement is the guiding principle behind the specification of an opera-
tional definition and the choice of a coherent set of measurement tools. Madans and colleagues
(2002) identified three major classes of purposes at the aggregate level in their research, ask-
ing general census questions on disability in the international context: (1) to provide services,
including the development of programs and policies for service provision and the evaluation
of these programmes and services, (2) to monitor the level of functioning in the population,
and (3) to assess equalization of opportunities. The assistive technology assessment (ATA)
process can be viewed as an aspect of the purpose described in point 1. Madans and col-
leagues stated that “provision of services at the population level includes, but is not limited
to, transportation, rehabilitation, providing assistive devices, long term care” (2002, slide 11)
and that the fulfilment of this aim “requires detailed information about the person and the
environment, as in the case of rehabilitation” (slide 11; please see also Madans and Altman
2006, slide 6). Questions about the need for assistive solutions and problems with accessibil-
ity are therefore at the heart of the assessment. Apart from all of this, the ultimate aim of the
