Limitations of Psychological Enquiry

Beyond the strengths and weaknesses already discussed for each individual method, psychological measurement as a whole faces three broader, more general problems. The first is the lack of a true zero point. In the physical sciences, measurement genuinely starts from zero, a table can be measured from a true zero and found to be, say, three feet long. Psychological measurement has no equivalent true zero: no person anywhere has 'zero' intelligence, since everyone possesses some degree of it, so psychologists are forced to arbitrarily fix some point as a working 'zero' and measure from there. As a consequence, scores obtained in psychological studies are never absolute in the way a physical measurement can be, they only ever have relative value, meaningful in comparison to other scores, not as an absolute quantity. This relativity shows up clearly when ranks are used as scores: if a teacher orders students 1st, 2nd, 3rd and so on by the marks they scored, the actual gap in ability between the 1st and 2nd rank holders need not be the same as the gap between the 2nd and 3rd; out of 50 marks, the topper might score 48, the runner-up 47, and the third-placed student 40, showing that equal rank-differences do not correspond to equal differences in the underlying ability. The second problem is the relative nature of psychological tools. A test is always built around the particular features of the context it was developed in; a test built for urban students, for example, may include items assuming familiarity with things like multi-storeyed buildings, aeroplanes or metro trains, which would put a child from a tribal area, more at home with locally familiar flora and fauna, at an unfair disadvantage, just as a test built in a Western country may or may not translate well to the Indian context; such tests need to be carefully modified and adapted to the characteristics of whichever context they are actually going to be used in, rather than being applied unchanged. The third problem is the subjective interpretation of qualitative data. Because qualitative data calls for genuine interpretation both by the researcher and by the person providing the data, different pe …