Assessment Instruments College: Assessment Instruments Psychology is the scientific study of the mind involving behaviour and cognitive processes, as well as how an organism’s physical state, mental state, and external environment affect them. Wundt (1902) asserts that Psych methods must be as exhaustive as those in chemistry and physics. The scientific study requires theoretical frameworks, testable hypotheses and empirical evidence.
Reliability refers to a measure’s ability to capture an individual’s true score. That is, to distinguish accurately one person from another. Reliability is about the consistency of a measure. An instrument is reliable if iterated measurements of the test under the same conditions are consistent. The result obtained each time a subject undergoes a test is approximately the same, hence, making it consistent. Validity refers to the question of whether the measurements are hitting on the construct that is acceptable to the tester. While we can obtain statistics for reliability, even for different types of reliabilty, validity is more of a global assessment based on the evidence available. Therefore, validity requires reliability, but reliability alone is not sufficient for validity.
A norming sample refers to a reference group whose scores become the standard point of comparison for future tests. It is a large population of test takers who constitute all the people for whom the study is intended. Means and standard deviations obtained by this group are the points of comparison for standard scores. Therefore, it is a sample used to standardize a test which is representative, large, current and appropriate to a test taker.
Reliability, validity and norming sample are key concerns in psychological research. One of the problems psychologists encounter is the lack of reliable measures for things they find to be of interest to them. It is always essential to find the reliability estimates for the measures one is about to use. This material is readily accessible in original and related articles and should be obtained before arriving at any conclusion. Assuming that the measures are valid, it is crucial to press for more reliable measures if we are to progress scientifically. This means letting go of supposed “standards” when they are no longer useful and finding ways to improve current ones.
Reliability is highly important in forensic assessment. This is because reliability tests whether the study satisfies its predicted aims and hypothesis. It also ensures that the results obtained come from the study and not any other possible extraneous variables. A reliable study is essential in developing further research. For example, a study on child attachments by Ainsworth and Bell (1970), ‘the Strange Situation Test’, was reliable because it gave consistent outcomes in subsequent studies. Children who exhibited certain types of attachments acted in predictable ways. This cleared the way for the study to be used to develop further research in this field. In addition, the reliability of this study extended globally, and it has become an accepted methodology universally. This shows how reliability can have an effect on the acceptance of a study.
Validity is a vital aspect in psychology. First, it provides an explanation of the relationship between two variables in a study. it outlines causes and effects between two variables. Secondly, validity explains to what extent the outcome of a study can be used to generalize a real world situation. For example, ‘The Obedience Experiment’ by Milgram (1963) which tested whether people would listen to an authoritative figure even if his instructions were unethical would not necessarily be valid. The results cannot be generalized since participants may have skewed their judgments as they were on a controlled environment. Therefore, without validity, we cannot identify causation. hence, results cannot be generalized.
Howitt, D. &. Cramer, D. (2005). Introduction to research methods in psychology. Harlow, England: Pearson/Prentice Hall.
Richmond, R. (1997). Psychological Testing. A Guide to Psychology and its Practice. Retrieved September 17, 2012, from http://www.guidetopsychology.com/testing.htm
Wundt, W. (1902). Principles of physiological psychology. Classics in the history of psychology. Retrieved September 17, 2012, from http://psychclassics.yorku.ca/Wundt/Physio/