Psychology Report: Methods for Assessing Test Reliability and Raters

This report explores the concept of test reliability, which is crucial for evaluating the quality and usefulness of tests. It defines reliability as the consistency and dependability of a test in measuring a specific characteristic. The report details two key methods for assessing reliability: the test-retest method, which examines the stability of scores over time, and the alternate-form method, which assesses the consistency of results across different test versions. Additionally, the report explains how to test the reliability of raters using Kappa statistics, a method that accounts for chance agreement. The report concludes by emphasizing the importance of choosing the appropriate method for measuring reliability, whether it's assessing the stability of test scores or ensuring consistency among different raters.

Running head: ASSESSING RELIABILITY 1
ASSESSING RELIABILITY
Name
Institution

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ASSESSING RELIABILITY
Introduction
Test reliability is a technical property of a test whose aim is to express the quality as well
as the usefulness of a test. It is meant to determine how dependent and consistent a test measures
a feature. For instance, a test that yields the same results for an individual that repeats a test is
regarded as having measured a characteristic reliably. This short paper defines some of the
methods used to test reliability such as test-retest and alternate form method. Besides, it explains
how I would go about testing the reliability of raters.
Test-retest Method
The test-retest method of reliability shows a test score’s repeatability as time passes.
Also, the method seeks to determine the stability of a characteristic as well as the construct that
is being measured using the test. Some of these constructs are regarded as more stable compared
to others (Liu, Xu & Lu, 2013). For instance, a person’s reading ability is observed to be more
stable over a given time compared to the same person’s level of anxiety. As a result, it would be
normal to expect higher test-retest reliability coefficient on the first construct than when
measuring anxiety. When assessing test-retest reliability the same measure is used on a group of
individuals at the same time and using the same measure on the same group once again at a later
date. Doing this requires using a scatterplot as well as computing Pearson’s r to show the
correlation between the scores (Choe, et al., 2017). Good reliability is indicated by a test-retest
correlation that is +.80 and above. A high test-retest correlation mostly occurs when the construct
under observation is consistent over time. The benefits associated with this method is that it can
be used in different situations conveniently.

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Alternate-Form Method
The alternate form technique is used to indicate the likelihood of consistency of test
scores if an individual engages two or more types of tests. The method is also known as
Equivalent form reliability, parallel form reliability, or comparable form reliability. Determining
reliability through this method requires using two distinct but equivalent versions of a test
(Thomson & Oppenheimer, 2016). The term alternate form means that the form is similar based
on objectives, length of the test, content, difficulty level, format, and discriminating value of the
items. A high alternate form reliability coefficient shows that the different types of tests are very
alike. This means that basically, there is no virtual difference in the type of version of the test
that an individual is supposed to take. However, in the case of a low alternate form reliability
coefficient, it shows that that the different versions of a test do not compare. This is to mean that
the versions are likely to be measuring different things (Nawafleh, et al., 2013). As a result, they
cannot be used as alternatives. Compared to the test-retest method, the alternate form method is
advantageous in that it makes sure that the same test is not duplicated.
Testing Reliability of Raters
I would use the Kappa statistics to test the reliability of raters. Inter-Rater reliability
determines the number of times rater A confirms rater’s B findings. The method is effective
compared to the traditional methods such as the percent agreement that does not take into
account chance agreement (Shaffer, et al., 2013). To test the reliability of raters using the Kappa
agreement, I would first calculate the proportion of agreement. To do this, the total agreement is
divided by the total number of raters. Next, the chance agreement is calculated, and it entails
multiplying the rows with the corresponding column proportions as expressed in the contingency

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table. The results are then summed up (Cools, et al., 2014)). The Kappa agreement aims at
eliminating chance agreement from the observed agreement and later dividing the non-chance
agreement with the total number of the non-chance agreement. The Kappa coefficient is the most
effective in determining the reliability of raters in data that belongs to two classes.
Conclusion
Determining the reliability of a test can involve four methods, two of which have been
discussed above, - test-retest method and alternate form method. The test-retest involves
administering the same test twice to a group of individuals within a given interval. The results
are then correlated and the correlation coefficient helps measure stability. The alternate form
method entails using two different but equivalent methods in testing reliability. To effectively
measure the reliability of raters, the Kappa coefficient would be the most effective tool. This is
because the technique eliminates the chance agreement from the observed agreements.

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References
Choe, A. S., Nebel, M. B., Barber, A. D., Cohen, J. R., Xu, Y., Pekar, J. J., ... & Lindquist, M. A.
(2017). Comparing test-retest reliability of dynamic functional connectivity
methods. Neuroimage, 158, 155-175.
Cools, A. M., De Wilde, L., Van Tongel, A., Ceyssens, C., Ryckewaert, R., & Cambier, D. C.
(2014). Measuring shoulder external and internal rotation strength and range of motion:
comprehensive intra-rater and inter-rater reliability study of several testing
protocols. Journal of Shoulder and Elbow Surgery, 23(10), 1454-1461.
Liu, P., Xu, F., & Lu, H. (2013). Test–retest reproducibility of a rapid method to measure brain
oxygen metabolism. Magnetic resonance in medicine, 69(3), 675-681.
Nawafleh, N. A., Mack, F., Evans, J., Mackay, J., & Hatamleh, M. M. (2013). Accuracy and
reliability of methods to measure marginal adaptation of crowns and FDPs: a literature
review. Journal of Prosthodontics, 22(5), 419-428.
Shaffer, S. W., Teyhen, D. S., Lorenson, C. L., Warren, R. L., Koreerat, C. M., Straseske, C. A.,
& Childs, J. D. (2013). Y-balance test: a reliability study involving multiple
raters. Military medicine, 178(11), 1264-1270.
Thomson, K. S., & Oppenheimer, D. M. (2016). Investigating an alternate form of the cognitive
reflection test. Judgment and Decision making, 11(1), 99.