Can Someone Please Explain a "Curve"

<p>Sorry if this is the wrong place...I just don't get it. Are they good or bad?</p>

<p>From what I'm hearing...it seems it kinda changes your grade. Like...these examples:</p>

<p>1 - I read about a lab that is "curved" so that only the top 20% get A's. Does that mean if I get a 92% and everyone else gets a 95%....even though 92 should be an A, I won't get an A because I'm not in the top 20%? </p>

<p>2 - The opposite...what if I get a 77 and everyone else gets a 75. Does that mean I get an A...even though a 77 should be a C?</p>

<p>Thanks so much..</p>

<p>1-yes
2-yes</p>

<p>Holy crap! That sounds awful!</p>

<p>So I could work my butt off for an A...and get it taken away!? That's fair!?</p>

<p>The idea is that you are graded against your peers, not an arbitrary numbering system. Most professors in early level classes will only curve you up, so that if the class average is below, say, 75, he'll give enough points to raise the average to that number, while if it's above a 75 he'll not touch the grades. The "20%, 92 can get you a B" thing is more reserved for stuff like law school in my experience. The curve will usually work in your favor.</p>

<p>Now don't even get me started on T-scoring, I can't even begin to explain that one.</p>

<p>My D just finished her sophomore year, along with two semesters of <em>killer</em> organic chemistry that nearly did her in. The 4 major tests were so difficult that the the curve was at rock bottom. For one of them, "A" went down to 75 and "C" went down to 29!! Can you imagine getting a 29 on a test, and then finding out you passed the test? Now, I think that means either that the material covered on the test was a lot harder than what they learned in class, or the professor was not a very good teacher. Either way, D got a B+ first semester, and a B- second, and was thrilled just to have passed and have it behind her. This from a girl who NEVER had less than an A on a report card in her life, and had never even received a B on a paper.
Guess that's what happens when the big fish in the pond joins a bigger pond <em>full</em> of big fish! :)</p>

<p>Hmm..so it's helpful MORE often than it hurts?</p>

<p>Earlier on yes, and in less competitive programs yes. Like I said though, in extremely competetive fields it can hurt you more than it helps. Think about it though, if the class average is a 95 and you're getting a 91, should you really be getting the same letter grade as the ones getting a 99?</p>

<p>^ Precisely. Besides, when most people talk about a curve it's in a positive way. Usually they'll specify a "deflating curve" when talking about one that restricts an A to 30% of the class, B to 50%, etc etc. Inflating curves are most often found in sciences courses, where the average grade often ranges from 60-70 on tests.</p>

<p>Deflating curves are nice anyway simply because they force a greater distribution of grades.</p>

<p>It's amusing that, with the direct question being to explain what a curve is, nobody has yet bothered to break out the actual explanation of fitting grade distributions to a Gaussian curve and assigning marks based on that. So I'll do it:</p>

<p>Prof gives his 200 person class a midterm. Ends up with a median grade and a standard deviation of grades. Says "I'm going to set the median grade at just below a B+, 1 1 SD above the median an A, etc." and assigns letter grades according to where the students' Z-scores (standardizes a normal variable to the same scale, where mean is 0 and standard deviation is 1).</p>

<p>Whether it benefits you or not really depends on your professor, the department's grading policies and your classmates. Here at Princeton, As are capped at ~30% of grades per department. Departments like to give more As in upperclass courses, so in the lower courses the curve often works against you, because you must do much better than the class to get an A. However, if you're smarter than your peers in a difficult class, it can be to your advantage to get that A when you only got 77 on the final.</p>

<p>lol my calc teacher is a UCSD alum. He told me he got a 7% on his O-Chem final. But the class average was a 5% so the curve gave him a C.</p>

<p>How does one get 7% on a final??? Guessing should give you a better grade than that!</p>

<p>Guessing only works if it's a multiple choice test or if you have some idea how to answer the question. That's not always the case.</p>

<p>The problem with curves (curving grades up, at least) is that they reward those who do the worst the most. Not to be annoying, but a kid who gets a high grade may only get a one or two point benefit from a curve, whereas someone down at the bottom of the will get far more points back. It's almost like trying to make people seem closer in skill level than they really are. (Not to mention the whole issue that you might have a class of very intelligent people/ very unintelligent people, so you wind up with a big curve when people actually deserve more/fewer points than they recieved.) That's why I prefer wieghts. The better you do the more you are rewarded.</p>