Assignment:
The disadvantage of utilizing a single statistical score as a measurement of multiple cognitive abilities
Many psychological tests, such as the Wechsler Adult Scales of Intelligence-Fourth Revision, provide a composite score that is intended to represent a summary of multiple cognitive abilities. For the Wechsler Scales, this score is the "Full Scale Intellectual Quotient." Although this score is not technically a statistical mean of the subtest scores, it is subject to the same potential liability of the statistical mean, that is, it may not accurately represent a client's cognitive abilities. A clinician must be able to evaluate whether or not this Full Scale Intelligence Quotation accurately represents an overall summary of the client's cognitive abilities. For example, if there are large differences among the subtests of an individual's score then the overall score will not be representative of these abilities, similar to the limitation of the statistical mean in representing central tendency when the distribution of scores contains very high or very low scores. It poses the questions: Do scores that represent a summary of multiple abilities of an individual accurately represent the pattern of the individual's abilities? What are the advantages and disadvantages of using composite scores to represent an individual's level of cognitive functioning?
Give description of one advantage and one disadvantage of using a single score or statistic to represent multiple constructs or abilities. Then describe one instance in which you might use each of these measures and explain how you would use them.