Krider Curve
The Krider Curve was developed by Dr. Daniel W. Krider,
Professor of Mathematics, Concord College, Athens, WV. The curve coerces
grades into forming a distribution which more closely resembles a Normal
Distribution. This is a partial solution to the problem of class grades
tending to be skewed toward the lower values. The Krider Curve forces
symmetrical clustering about the mean (property of central tendency) and
smaller variance within the scores (less dispersion).
Mathematical Derivation
Given the following:
The following formula is applied to each individual student grade:
This is equivalent to averaging two X values with one grade of a 100. The
lower scores receive a larger curve than the upper scores. An appropriate
action when one considers that poorer students require more help. The
curve ensures that a student will never surpass another student who scores
higher.
Alpha can be set to achieve a desired class mean.
Where:
The formula for deriving alpha's value for a desired mean:
