I was thinking about something only tangentially related to grading, when it struck me that the way we go about generating student grade point averages is the kind of mind-bogglingly stupid system that requires lots of smart people working together to produce. Two very different groups of smart people, with very different ways of looking at the world.<\/p>\n
As a scientist, the starting point for assigning grades is generally a set of scores on a bunch of individual assessments. These are generally combined to form some sort of weighted average, which can be expressed as something like a percentage of the total possible points earned. This percentage is then converted to a letter grade (possibly with letter-plus and letter-minus steps, depending on the institution). Then those letter grades are converted back to numbers based on the four-point scale, and those numbers are averaged to produce an overall GPA. Which is reported to three decimal places so we can rank-order students.<\/p>\n
But from a signal-processing sort of standpoint, this is remarkably stupid. I have what is basically a continuous analog signal in the initial percentage grade, which is then crudely digitized into a letter grade with a limited set of discrete steps, and then converted back to an analog signal by averaging a bunch of letter grades. The middle step of converting to a discrete letter scale then converting back is pointless at best, and probably introduces extra noise. You’d be much better off averaging together the original percentage scores.<\/p>\n
But, of course, I say that because I’m a scientist, and my classes tend to involve lots of grades that are easily rendered into a roughly continuous numerical format. The letter-grade scale is a foolish and clumsy add-on to this. Faculty in “the humanities,” though, and others teaching classes where the vast majority of the final grade is determined from a single paper are much better served by the cruder letter-grade scale– they’re starting with grades that naturally fall into a smaller number of reasonably discrete categories.<\/p>\n
But, of course, we have to do something to summarize the performance of students in a compact manner, and employers and graduate schools want rank-ordered lists of class standing, and the false precision of extra decimal places has a seductive allure. so we’re stuck with this foolish system of crude and pointless intermediate discretization…<\/p>\n","protected":false},"excerpt":{"rendered":"
I was thinking about something only tangentially related to grading, when it struck me that the way we go about generating student grade point averages is the kind of mind-bogglingly stupid system that requires lots of smart people working together to produce. Two very different groups of smart people, with very different ways of looking… Continue reading GPA’s Are Idiotic<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8,13,9,11],"tags":[],"class_list":["post-9966","post","type-post","status-publish","format-standard","hentry","category-academia","category-education","category-math","category-science","entry"],"_links":{"self":[{"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/posts\/9966","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/comments?post=9966"}],"version-history":[{"count":0,"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/posts\/9966\/revisions"}],"wp:attachment":[{"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/media?parent=9966"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/categories?post=9966"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/tags?post=9966"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}