Psychometrics as a Branch of Psychology - Essay Example

Psychometrics Introduction Jones and Thissen 2007 p define psychometrics as “any branch of psychology concerned with psychological measurements”.Such a definition makes psychometrics an inclusive feature of those branches of psychology where tests and measures are employed for better under standing of behavioural traits and functional aspects of an individual. Tests of behavioural traits and functional aspects of an individual are undertaken so that an attempt could be made to predict behaviour and performance. From a functional perspective psychometrics may be employed for occupational and educational measurement purposes. The tests used are designed strictly for this purpose and has no relevance to anything else other than the purpose for which it was created (Rust & Golombok, 1989). Psychometrics Measurement in psychometrics can be taken as the conversion of abstract constructs into concrete variables on the basis of a clear set of rules and arises from the conjecture of McCall 1939 p.15, that “anything that exists in amount can be measured.” Tests form the essential feature of the means to measurement in psychometrics. A test may be taken as a standard procedure in an attempt to sample behaviour and describe it in terms of categories or scores. A true test incorporates norms and standards in relation to the scores that assist in the prediction of behaviour and performance. An unstandardised test has confounding factors in it, which interact with the performance and as a result has a negative impact on the ability to evaluate performance. Psychological testing attempts to ape measurements in the physical measurement, where numbers are ascribed to demonstrate levels of some feature like temperature or weight. Tests through its scores or evidence make it possible to assess whether an individual belongs to a particular category or group and to evaluate the quantum of trait or quality that is possessed by the individual. There are two caveats that govern any test. The first caveat is that error is inherent to a test result and that the measurement obtained is not a reflection of the true score, but a reflection of the sum of the true score and the error, which may be positive or negative. The second caveat is that psychological test scores are not a measure of physical reality and are representative of abstract concepts. For example the Intelligence Quotient (IQ) does not really exist, but is a useful abstract concept for predicting success in academics or career. Test scores are interpreted through the comparison against a set of prescribed scores. Test developers set out the norms for comparison that include a summary of test results for a group of representative test takers. Some test scores are predictive in nature. In such tests the interest of the tester lies more in the additional behaviours that come from the predictive nature of the tests than in the test items represented in the test. The WAIS IQ to test to predict academic achievement is an example of this. A test score by itself is useless unless there is a frame of reference through other scores. Norms and standardization provide this frame of reference. A norm group can be taken as the group of individuals on whom the test is going to be applied. For example such a group may consist of a group of students prior to entry and the test applied the college entrance test. The objective here would be for the test to create a distribution of raw scores that the tester can use as a frame of reference for the individual scores received from the test. Age and grade norm are examples of norms used. Reliability and validity are two key issues in psychometric tests. An example of the reliability issue can be seen when I.Q tests are repeated in succession and the scores correlated. The reliability will falsely appear to be very high, as the participants would remember the responses that they had provided. A way around this is to create a time gap of at least three months before repeating the tests, which however may not be practical in all groups. Kline 1986 p.4, proposes that “a test is valid if it measures what it claims to measure.” The means to establish validity of a test is not easy. There are two means to establish the validity of a psychometric test, namely face validity and concurrent validity. Face validity does not establish true validity, as face validity considers a test to be valid, if it appears to measure what it is supposed to measure. Concurrent validity on the other is a more true measure of validity, for it correlates the test to other tests that are known to provide valid measures (Kline, 1986). More consistent means to establish validity are content validity, which is the extent to which the test successfully measures that which it is purported to be derived from and construct validity, which is the extent to which the test is provided support by the theory of the construct. Tests come in many forms for different purposes and can be differentiated in several ways. One way is from their frame of reference namely norm referenced or criterion referenced. Tests may be administered individually or to a group of individuals at one time. There are several types of test, which include intelligence tests that test the performance ability in aspects like word definitions, general knowledge, memory and numerical operations; aptitude tests that attempt to predict success in studies or occupation, like S.A.T before college admissions in the U.S.A and achievement tests to measure the quantum of learning, success or accomplishment. The key difference between achievement and aptitude tests is that achievement tests relate to the past, while aptitude tests attempt to predict the future. Other types of tests are creativity tests designed to evaluate the ability for new ideas, insights or artistic creations; personality tests that are employed to measure traits and qualities predictive of future behaviour and behavioural procedures that employ checklists, rating scales and observation to evaluate the behaviour of an individual. There are several uses for psychometric tests. Self-knowledge, diagnosis and treatment, programme assessment, research and classification are some of the common uses for psychometric tests. Conclusion Psychometrics involves measurements that are used in any branch of psychology. In psychometrics abstract constructs are taken and converted into measurable variables of behavioural traits and functional aspects of an individual. These measures find several uses to provide a better understanding of an individual. Literary References Jones, L. V. & Thissen, D. 2007, ‘A History and Overview of Psychometrics’, in Handbook of Statistics – Psychometrics Vol.26, eds. Calyampudi Radhakrishna Rao & S. Sinharay, Elsevier, Amsterdam, pp.1-22. Kline, P. 1986, ‘A handbook of test construction: introduction to psychometric design’, Routledge, London. McCall, W. A. 1939, Measurement, The Macmillan Company, New York. Rust, J. & Golombok, S. 1989, ‘Modern psychometrics: the science of psychological assessment, Routledge, London. Read More