Percentages in assessment
"What percentage constitutes a passing grade?" For example, some people might say 60%, others might say 70% is higher, and others suggest that 80% represents "higher quality" education.
The fact is that the actual percentage figure is completely arbitrary. An assessor could easily dumb down all questions in order to require 100% correct. Similarly, an assessor could make them all so difficult that 20% correct is a good result.
In norm-based assessment, what really matters is the percentile needed to be deemed a passing grade. In norm-referenced assessment, assessors use a scaling adjustment so that, for example, the 25% of students with the lowest percentages are failed, the middle 50% do satisfactorily, and the top 25% get distinctions.
In a competency-based system, however, it is the other way around. First, write competencies to define a passing level of performance. Then set the testing system so that a pass fits the competency. In competency-based assessment, all knowledge is required so we can legitimately ask: "If it doesn't matter whether students get a particular question wrong, then nobody needs to get it right to pass. So why are you asking it?" In other words, it is quite legitimate to ask for 100% in these cases.
Some systems have it both ways; they use a rubric for assessors to classify answers as "unsatisfactory," "satisfactory," and one or more levels of exceptional. Other have several stages:
- Early questions only settle students into the testing environment.
- The next batch of questions tests the basics, and represent the competency standard. Students must get them all correct to pass.
- The following batch of questions are more difficult; their purpose is to enable students to get a grade above the minimum pass.