What does validity mean?
The term validity can be defined in two ways: (a) the ability of the test to assess what it is supposed to assess, and (b) the ability of the test to allow valid inferences to be drawn from its results. These are in fact two ways of saying the same thing. For example, suppose we are using a personality questionnaire which contains a dimension called “Social Confidence”. We firstly wish to know that the score on this dimension really does reflect the amount of social confidence a person has – or putting it differently, that people with high scores on this dimension really will show more confidence in social settings than people who score low on the dimension. Alternatively, we might say that we want to be confident in any inferences we make about the person on the basis of their score on this dimension. For example, if we wish to make the inference that people who score high on this dimension will perform well in customer service jobs, then we would want to know that this would be a cor
