Using Norms in the Interpretation of Test Results
As scientists in the field of psychology we seek to understand, predict and control human behaviour. In clinical, industrial and educational settings psychologists make attributions as to the cause, or likelihood, of behaviour based on evidence gathered from observational, interview, and assessment data.
Research into the process of making attributions and building theories or schema of people’s behaviours shows the process is fraught with difficulties, even with professionals involved (Meehl, 1954; Sawyer, 1966). Attributions are seldom made on the full range of available data as Heider (1958) or Kelly (1967) would have liked to believe. Difficulties include:
- characterising information on the basis of preexisting theories (Nisbett and Ross, 1980).
- extreme examples overly influencing judgements (Rothbart, Fulero, Jensen, Howard, & Birrell, 1978).
- people being unaware of the effects of small (Nisbett & Ross, 1980) or unrepresentative samples (Hamill, Wilson, & Nisbett, 1980).
- underutilising base rate information (Hamill et al., 1980).
Of all the problems of building our judgements about people the last point is arguably the easiest to control. Through using objective assessment techniques (after evaluation of the psychometric qualities of the tools) we can make judgements confident that the results are going to give a measure of the consistency of an individual’s behaviour (based on the reliability of the tool and validity of its predictions) and its uniqueness (based on the comparison of the result to appropriate groups).