Page 34 - teachers.PDF

• They do not adjust for differing test difficulties.
• They do not contain a frame of reference for indicating how well a student is
performing.
• They can mislead teachers, students and others into thinking the percent correct a
student receives is the percent of the content the student knows or can do.
Objective percent correct scores
Objective percent correct scores tell you the percent of the items measuring a single objective that a student answers correctly. Because objectives and items can vary in difficulty, this score is of limited value for determining whether a student has mastered a learning objective. Indeed, the objective percent correct scores is really a percent correct score for a reduced test domain (reduced to a single objective).
You might interpret the objective percent correct score in relation to an expected objective percent correct. Expectations are sometimes based on curricular goals, last year's performance, or national averages. But, since different collections of test items will not be equivalent in difficulty, comparing a student’s objective percent correct with another student’s or with an expectation should only be done when the items are identical or equivalent.
Expectations can be used to convert objective percent correct scores to objective mastery scores. When the expectation is met or exceeded, the objective is mastered. Conversely, when the score is lower than expected, the objective is not mastered.
For example, suppose a test contains eight whole-number addition problems and a student answers seven of them correctly. That student's objective percent correct score is 87.5%. If you feel that answering, say,, three out of every four questions correctly reflects mastery, then this test score indicates that the student has mastered the objective.
What are the advantages of objective mastery scores?
• They are easy to compute.
• They adjust for differing numbers of items per objective.
• They help you diagnose specific individual strengths and weaknesses.
• They provide a skill-based approach to classroom grouping and school-based
curricular emphasis.
What are the limitations of objective mastery scores?
• They require a fairly large number of items (usually more than ten) for each objective. The fewer items there are per objective, the greater is the likelihood of mistaking masters from non-masters and vice versa.
• Expectations are not always easy to define. The national average is not always a good basis for determining expectation.
• They do not indicate the degree or level of skill that the student has attained; they only indicate the status of mastery or non-mastery.
Rudner, L. and W. Schafer (2002) What Teachers Need to Know About Assessment. Washington, DC: National Education Association.
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