For one to properly interact with their environment, they need to possess capacity for intellectual and rational thinking. This is the primary basis of the Wechsler Intelligence Scale (WIS). Essentially, this scale is used as a tool for measuring one’s intelligence level (Watkins & Smith, 2013). Two versions of the scale are available. One of the versions measures the intelligence level of adults while the second version was developed for children. The WIS continues to play an important role in psychological testing. This scale is used to evaluate the cognitive endowment of an individual. It can also offer insights into whether an individual has developed a disorder. For example, insights gained from the scale have been used to determine retardation. The scale allows practitioners in the mental health profession to identify individuals with special needs. The Wechsler Intelligence Scale is still in use today. This fact indicates that there is consensus within the psychology and the larger mental health profession that this scale is valid, reliable and that it adheres to established norms. In this paper, the validity, reliability and the adherence to norms of the scale are investigated. The paper also explores the importance of these parameters.
Validity
Before a test is accepted for application, it must be established that it is actually valid. Essentially, valid concerns whether the outcomes of a test can be accepted (Loewenthal & Lewis, 2015). This means that the test must actually measure the parameter for which it was developed. For instance, a test that is intended to evaluate intelligence or emotional response should actually measure these issues. There are various forms of validity. There have been attempts by the scientific community to assess the validity of the Wechsler Intelligence Scale. In the following discussion, focus is given to the results of studies that have explored the validity of this test.
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Construct validity
Construct validity is one of the different forms of validity. Essentially, this type of validity investigates whether a test actually measures the variable for which it was intended. The construct validity of the Wechsler Intelligence Scale was the subject of a study conducted by Gary Canivez. For his study, Canivez examined data obtained from a sample of school children. He used first factor models and subjected these models to confirmatory factor analysis (Canivez, 2015). The results from his study indicate that the WIS test indeed possesses construct validity. Canivez is not the only individual who has examined the construct validity of the WIS scale. Numerous other scholars have also investigated the construct validity of the test. The findings from their efforts suggest that the test possess construct validity. These findings are important because they provide a basis for the continued use of the scale. Were it that the investigations revealed that the WIS scale lacked construct validity, it would be unwise and pointless to continue using it. Now, professionals can confidently rely on the test for evaluating the intelligence of individuals.
Structural validity
A test that accurately measures a variable needs to possess structural validity. Structural validity refers to “the degree to which scores… are an adequate reflection of the dimensionality of the construct being measured” (Styck & Watkins, 2016). Styck & Watkins set out to determine if the WIS possessed structural validity. They focused on the version of the test that is meant for children. They narrowed down on children with disabilities as the subjects of their focus. The procedure that the duo applied involved conducting confirmatory factor analysis on data obtained from the subjects. They also applied the bifactor model and fitted the general intelligence breadth factor model to the test. The results from his investigation allowed him to conclude that the WIS test possesses structural validity. Nelson Jason, Gary Cavinez and Marley Watkins collaborated on another study in which they examined the structural validity of the WIS test. They applied the same procedure that Styck and Watkins used for their study. They obtained the same result: the structural validity of the WIS test is not in question (Jason, Cavinez & Watkins, 2013). Therefore, it can be concluded that structural validity is present in the WIS test. Structural validity is as important as construct validity. The fact that the WIS test has been established to possess structural validity means that professionals can continue to use it for a wide range of populations.
Incremental validity
It is important for a tool used for psychological testing to keep up with changes. It is for this reason that psychological tests should possess incremental validity. Incremental validity regards the capacity of a test to measure variables that go beyond what assessment tools that are being used currently are capable of. Jason, Cavinez and Watkins extended their study to beyond the structural validity of the WIS test. They also investigated whether this test possessed incremental validity (Jason, Cavinez & Watkins, 2013). They used the same procedure that they employed in assessing the structural validity of the WIS test. Their findings indicate that the test has incremental validity (Jason, Cavinez & Watkins, 2013). What this means is that even if changes are witnessed, the WIS test will remain relevant. This is important because it spares professionals in the field of mental health the need of developing new tests in response to the changes.
Reliability
Reliability is concerned with consistency and stability (Loewenthal & Lewis, 2015). A reliable psychological test is one that allows for consistent and stable results to be obtained every time the test is used. As is the case with validity, there are various forms of stability. Reliability is important as it allows those administering tests to be certain that they will obtain consistent results. Consistent results allow them to make comparisons between different groups. For example, thanks to consistency, it is possible for results obtained in different periods to be compared. In the following discussion, an examination of the reliability of the WIS test is conducted.
Ryan Joseph and Charles Ward joined hands to investigate the reliability of the WIS test. To demonstrate that this test is reliable, they obtained data from a group of adolescents and adults (Ryan & Ward, 1999). The data contained a wide range of issues which included block design, picture completion and identification of similarities. By examining this data, they were able to conclude that the WIS test is reliable (Ryan & Ward, 1999). This conclusion presents implications for the mental health profession. It means that the members of this profession can rely on the test to offer them consistent results. This is important because the professionals can expect more or less the same results for different populations.
In an earlier discussion, it was noted that there are various forms of reliability. Test-retest is among these. Basically, this form is concerned with the consistency of psychological tests with time. This means that this form of reliability examines whether time has any effect on the reliability of a test. There have been attempts to understand if the results obtained from the WIS test are affected by the passage of time. Some of these attempts can be attributed to Watkins Marley and Smith Lourdes. They conducted a study that addressed a number of issues. The test-retest reliability of the WIS test is among these issues (Watkins & Smith, 2013). They determined that this test lacked the test-retest reliability. They arrived at this conclusion after evaluating the scores of children from two different school districts. Their finding is both interesting and concerning. It is interesting in that it raises questions about whether the mental health profession should continue using the test given that it has been shown to lack test-retest reliability. It causes concern because it makes one wonder whether the results that have been obtained in the past are acceptable. It is important for the mental health profession to continue to investigate the reliability of the WIS test. If very many examinations consistently reveal that the test lacks test-retest reliability, then the mental health profession will be forced to rethink its use of the test. The profession may be forced to abandon the test entirely. Alternatively, it is possible for the profession to adjust the test so as to ensure that it possesses test-retest reliability. This is clearly the better option as it will allow practitioners to continue using a test that has proven to be effective over the many years that it has been in application.
Norms
Most tools that are used for psychological testing rely on the scores of test takers. The scores of individual test takers offer little meaning. It is when these scores are compared to the scores of the general subject population that some meaning can be obtained. The position of an individual score in relation to other scores is the basis of norms of psychological testing (Harrison et al., 2015). The WIS test is similar to other tests in that it allows for insights to be gained by placing individual scores relative to general scores. There have been attempts to understand the effect that different norms have on the results that the test yields. For instance, scholars have wondered how the results change when a different subject population is used. Allyson Harrison and her colleagues are among the scholars who have examined the role that norms play. They compared Canadian and American norms. According to their findings, norms appear to have an influence. They found that the norms obtained from Canadian subjects were lower than those of American subjects (Harrison et al. 2015). This finding is important as it provides lessons for practitioners. It is important for practitioners to examine the characteristics of the subject populations that they wish to apply the WIS test to. It is vital to ensure that the characteristics allow for accurate results to be obtained.
Lessons learnt and conclusion
The investigation of the WIS test has provided numerous lessons. One, it has firmly established that the test is valid. This means that the results obtained when the test is used can be trusted and accepted. It also means that mental health professionals can continue to use the test without being concerned that the results could be wrong. Two, the investigation has established that the WIS test is reliable. The implication of this is that practitioners can hope to obtain consistent results. However, it was noted that the test lacks test-retest reliability. The meaning of this is that the results obtained from the test could change with time. While this means that the WIS test is imperfect, it does not justify discarding the test entirely. The practitioners in the mental health profession should work together to ensure that the flaws in the test are addressed. They can do this by adjusting the test to suit their particular needs and objectives. In conclusion, the Wechsler Intelligence Scale continues to be a useful tool. It allows for the intelligence of individuals to be measured. While it is true that the test lacks some forms of reliability, the test remains largely useful and effective. For this reason, practitioners can continue to use it with confidence. However, they should exercise caution when using the test since it possesses some flaws.
References
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