Reliability and Validity Worksheet
Instrument Reliability
A reliable instrument is one that is consistent in what it measures. If, for example, an individual scores highly on the first administration of a test and if the test is reliable, he or she should score highly on a second administration.
Imagine that you are conducting a study for which you must develop a test in mathematics for 7th-grade students. You develop a 30-point test and distribute it to a class of 12, 7th-grade students. You then administer the test again one month later to the day. The scores of the students on the two administrations of the test are listed below. Use Microsoft® Excel® or IBM® SPSS® to create a scatterplot with the provided scores, formatted as shown in the example graph. What observations can you make about the reliability of this test? Explain.
30-POINT TEST 30-POINT TEST
(FIRST ADMINISTRATION) (SECOND ADMINISTRATION)
A 17 15_______________
B 22 18_______________
C 25 21_______________
D 12 15_______________
E 7 14_______________
F 28 27_______________
G 27 24_______________
H 8 5_______________
I 21 25_______________
J 24 21_______________
K 27 27_______________
L 21 19_______________
What Kind of Validity Evidence: Content-Related, Criterion-Related or Construct-Related?
A valid instrument is one that measures what it says it measures. Validity depends on the amount and type of evidence there is to support one’s interpretations concerning data that has been collected. This week, you discussed three kinds of evidence that can be collected regarding validity: content-related, criterion-related, and construct-related evidence.
Each question below represents one of these three evidence types. In the space provided, write content if the question refers to content-related evidence, criterion if the question related to criterion-related evidence, and construct if the question refers to construct-related evidence of validity.
- How strong is the relationship between the students’ scores obtained using this instrument and their teacher’s rating of their ability?
- How adequately do the questions in the instrument represent that which is being measured?
- Do the items that the instrument contains logically reflect that which is being measured?
- Are there a variety of different types of evidence (test scores, teacher ratings, correlations, etc.) that all measure this variable?
- How well do the scores obtained using this instrument predict future performance?
- Is the format of the instrument appropriate?
RESPOND TO YOUR TWO FELLOW CLASSMATES BELOW IN A 175 WORD COUNT EACH WITH SEPARATE REFERENCES BELOW:
Rick Lucero
There are four ways of measuring reliability. These are the inter-rater reliability, test-retest reliability, parallel forms reliability, and internal consistency reliability (Sauro, 2015). These are some of the most used methods used when it comes to establishing reliability. The four methods are different and similar at the same time which is a very useful thing to be. The inter-rater reliability is used in situations such as doing interviews and the raters would give consistent estimates of the same thing (Sauro, 2015). Test-retest is when the same questionnaire or test is given to the same person twice on two different occasions to see if the results line up the same (Sauro, 2015). Parallel forms are when you use similar questions or methods and see what results you get, because these should give the same kind of results since they are basically the same but a little bit different (Sauro, 2015). Internal consistency is when the items or questions that are asked measure the same construct and this leads to similar results (Sauro, 2015). They are all similar because they help us to find reliability. They are different because there are certain times and places that one may work and others do not. I personal like how the test-retest reliability works because it is a chance to see if some thing is going on and then you can retest it and see if this is right or not.
Sauro, J. (2015). How to measure the reliability of your methods and metrics. Retrieved from https://measuringu.com/measure-reliability/
Nalley Akinrefon
According to our reading, reliability refers to consistency with the tool of measurement (Cohen & Swerdlik, 2018) . There are three methods for establishing reliability. The first is test-retest, second, alternate or parallel forms of a test, and third is internal or inter-item consistency. The test-retest refers to taking a test for the first time and noting the score, then giving the same test to the same person at a later date (Cohen & Swerdlik, 2018). If a person does well on the test the first time he or she should do well the second time around. The test-retest method would be good for personality testing because our personality type does not change even though people change as they age. Alternate or parallel forms of test would give test takers equal scores from the first version to the alternate test. A parallel test is simply a different versions of a test that have been constructed so as to be parallel to the original test (Cohen & Swerdlik, 2018). A test can be reliable in one area and unreliable in another. Some methods of establishing reliability are, understanding the variance in test score, using standard deviation, true variance and error variance. The greater the proportion of the total variance attributed to true variance, the more reliable the test.
I would prefer the test-retest method because if a test is reliable and giving under the same circumstance one should receive the same or equal results. This method is simple, which I like.
Cohen, R. J., & Swerdlik, M.,E., (2018), Psychological Testing and Assessment, an Introduction to Testing and Measurement, McGraw-Hill Education
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