I don't understand the curve

[ZaneKaiser]

Can someone explain how a grading curve works? My Ochem professor curves his class but only gives us our raw grades, he won't tell us our curved score. So how exactly are we supposed to know where we stand in the class?

For example, our last exam average was a 60. I scored an 82, I have no idea if I got an A or B. Our prof did say the standard deviation was 15 points, but I haven't taken statistics so I don't know what that means.

I 'm not sure I like the idea of this system, students with low grades have no idea whether they should drop or not because they don't know if the curve will help them pass or not.

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[AlteredScale]

Can someone explain how a grading curve works? My Ochem professor curves his class but only gives us our raw grades, he won't tell us our curved score. So how exactly are we supposed to know where we stand in the class?

For example, our last exam average was a 60. I scored an 82, I have no idea if I got an A or B or whatever. Our prof did say the standard deviation was 15 points, but I haven't taken statistics so I don't know what that means.

I really don't like the idea of this system, students with low grades have no idea whether they should drop or not because they don't know if the curve will help them pass or not.

One standard deviation is a set above or below the average. So for the exam. one standard deviation above the average would be a 75 (60+15) while one SD below would be 45 (60-15).

You getting an A or B will depend on whether the professor sets the average as a B average or a C average. If 60 is a B, then you will get an A since you are above the standard deviation. If it's a C then you will get a B/B+ on the test.

Either way, you did great.

 

[Afford]

Usually, professors curve classes to a B, so the average person gets a B. If you're above the average, you'll get something higher than the average grade. I felt that most professors just arbitrarily set the curve to be X% of people get an A, etc. If you want to know your current grade, email him. I would guess that you're in the A- to A range.

 

[sunflower18]

My OChem class was curved to a B-/C+ I believe, but they didn't apply the curve until the very end of the semester, so there would have been no way for them to provide our "curved" scores as we went along since that wasn't going to be decided until after the final. They can usually guess where certain scores will fall, but at least in my class, there was some variation between the years (I think it'd be more consistent with a class size of ~200... When you're in a class of ~20, there can be a lot more individual sway).

 

[ski89]

Can someone explain how a grading curve works? My Ochem professor curves his class but only gives us our raw grades, he won't tell us our curved score. So how exactly are we supposed to know where we stand in the class?

For example, our last exam average was a 60. I scored an 82, I have no idea if I got an A or B. Our prof did say the standard deviation was 15 points, but I haven't taken statistics so I don't know what that means.

I 'm not sure I like the idea of this system, students with low grades have no idea whether they should drop or not because they don't know if the curve will help them pass or not.

One way to think of standard deviation is as a measurement of how spread out the test scores are. Or put more technically, how flat the normal distribution is. The higher the SD the more spread out the scores. In general I would say the greater the SD the better the test because it was successful in distinguishing the great students from the good students from the ok students from the poor students.

As far as a curve goes, some professors simply bump the raw average to the desired class average (usually 75-80%), or they take the highest score in the class and make that 100% and adjust everyone's score accordingly.

If I were you I would go talk to your prof in his/her office to discuss how you are doing.

 

[kraskadva]

This is a bell curve, with standard deviations:

This is what it looks like if the prof sets the average at a B:

If the prof is giving you the avg and the std.dev. then you don't need to understand much in the way of statistics to see where your grade is. And it sounds like you're doing fine in the class anyway...

 

[ZaneKaiser]

Well okay, that makes a lot more sense. Thank you all for explaining it to me. I'll email my prof. and ask him if he's setting the median to a C or C+/B-. Either way I think I got a B+ or A- on the test and am pretty satisfied.