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Understanding autism
Understanding autism

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4.1 Case studies and observational methods

The case study method, most often used by clinicians, involves careful, detailed observation of individuals (autistic children in this case) over a period of time, together with in-depth interview with the individuals, or with other family members. The clinician uses their expertise to interpret observed behaviour and other signs as carefully and objectively as possible in order to formulate detailed individual reports. But the choice of which individuals and which behaviours to observe, and the clinician’s own assumptions and expectations may nonetheless serve as sources of bias. Fully fledged observational methods, often used in research studies, may involve further steps to control or minimise such biases.

In a typical investigation, observations of a group of autistic individuals will be compared with observations of a comparable group of neurotypical people (people without autism). The neurotypical comparison group, known as a control group, is matched as closely as possible to the autistic group in terms of factors such as age, intellectual level and language ability. Thus any differences that emerge between the autistic and control groups can be attributed to autism, not some other group difference, such as age. Matching by age might seem straightforward, but is usually not sufficient to make a fair comparison, since autistic people may have language difficulties or be intellectually less able than neurotypical people of the same age. Specialised tests of language ability and/or intellectual ability (IQ), part of a systematic method known as psychometrics, are used to measure the functioning of those in each group. Psychometrics means the objective measurement of psychological abilities and traits, and includes tests of skills and knowledge, abilities, attitudes, personality traits and so on.

Other means to avoid observational bias may include an agreed observation schedule to avoid the researcher picking out just what appear to be the most significant behaviours, and ‘blinding’, a procedure in which those making and interpreting the observations are not told which participants have autism and which are neurotypical.