The video is the 8th video of a series of 10 in the SPOC “How to write test items for measuring student progress”.

The video discusses the fundamental concepts of educational testing and how to interpret test scores. A test is a tool used to estimate a student's ability, but since abilities are latent constructs, they cannot be directly measured or observed. A student's true knowledge and skills can only be estimated from observable data produced by the student, as in a test.

A test consists of three components: (a) questions (items) related to the construct we want to test, (b) rules for identifying correct responses, and (c) a scoring mechanism that is able to reflect the true abilities of the tests-takers.

There are also three steps involved in building a test: (a) writing sufficient numbers of items, (b) trialing the items on a relevant group of students, and (c) analyzing the item responses to see if they work well together as a test.
The content of the items is crucial. At the same time, the items should measure the same construct in the same way. If an item in a test cannot be measured on the same scale as the other items, it cannot be used in the test, even if its content is within the subject domain of the test.

The interpretation of a test result is also essential, as the test score is not the student's true ability, but rather statistical information about their responses. The video explains how to relate test results to a given scale and discusses the shortcomings of ordinal scales for measuring progress, including reference to the Toulmin structure of arguments.

The video emphasizes the importance of distinguishing between statistical facts and claims about student ability and cautions against drawing hasty conclusions from test scores.

The next video in this module 3 concerns varies perspectives on testing and the concepts of reliability and validity

Further reading

Reckase, M. D. (2017). A tale of two models: Sources of confusion in achievement testing. ETS Research Report Series; https://doi.org/10.1002/ets2.12171
Stevens S.S, (1946). On the Theory of Scales of Measurement. Science, New Series, Vol. 103, No. 2684 (Jun. 7, 1946), pp. 677-680. DOI: 10.1126/science.103.2684.677
Kane, M. T. (2013). Validating the interpretations and uses of test scores. Journal of Educational Measurement, Vol. 50 (1), pp. 1-73. https://doi.org/10.1111/jedm.12000
Messick, S. (1984). The psychology of educational measurement. ETS Research Report Series, Vol 1984 (1). pp. 55. https://doi.org/10.1002/j.2330-8516.1984.tb00046.x