The usual assumption in education is that grades follow some sort of normal curve. My question is about situations where the grade distribution curve is a rising one. More A's than B's, and more B's than C's, etc. In educational setting: Is there a name for this situation? Are there studies or methodologies related to it? Any references are welcome. (My question is not about the mathematical detail of a probability distribution function, it is about the occurrence of such distributions of grades in education, or about teaching styles that are related to them etc.)
The student grades could be following an exponential distribution or a Poisson distribution. Both of these distributions have been extensively analyzed statistically.
It is also possible that the distribution is one tail of a normal distribution, where the mean is greater than 100%.
Here are three scenarios that can result in such a grade distribution. The three scenarios can be combined:
a. The algorithm for solving problems is fault-tolerant. There are implicit or explicit checks built into each problem. If a student makes a small number of mistake(s), they will catch them in time, and not lose any points.
b. Multiple independent mistakes are required to mess up problem(s) badly enough that points are taken off.
The student population has been pre-filtered, so that only students in the bottom half of a bell curve are in the class.
The grading standards emphasize "allowing students to succeed" or "minimizing an achievement gap". In other words, the "bar is set low".
Standardized tests are designed to have bell-curve grade distributions. Some ways they do this are to:
- Have lots of chances to score small amounts of points.
- Have an average score that is in the middle of the possible range.
- Create time pressure. Slower students will score worse because they run out of time, or do not have time to check their work.
- Have lots of trick questions (especially questions with double-negatives). These questions tend to test "test-taking ability" or "general intelligence (IQ)" instead of the specific subject matter.
- Have lots of questions with an "obviously correct" answer that is actually wrong.
- Have a variety of difficulty levels of questions, so there are some questions that most students answer correctly, and some that most students answer incorrectly.
Although I have serious issues with "outcomes based" education, its philosophy does combat the pernicious notion that grades should have a normal distribution centered on "average."
It is not unreasonable to expect that most students will meet the learning objectives of a class. If most do not, then there might be something flawed with the preparation of the audience, or with the instructor, or with the purpose of the course. In this perspective, one might expect most grades to be A or B.