Quote Originally Posted by MarvinP View Post
Hi jpeg and welcome to the forum.

I used to teach math and bias against averaging or weighting percentages. Maybe you should read these before working on your girlfriends affections.
http://wiki.answers.com/Q/Can_you_average_percentages
http://www.ericdigests.org/2003-4/sc...ilization.html
http://statistics.laerd.com/statisti...dard-score.php
http://www.teachersandfamilies.com/o...nt/scores2.cfm

Sorry for not answering your question but I think more teachers should know it is just wrong to average percentages. I do believe more people should look at average student scores and standard deviations to help with grading.
thanks for the reply Marvin. She's actually a math teacher as well haha.

I originally planned to do the "total marks given / total marks maximum" option, but she would prefer to know where a student sits by averaging out the percentages. While I didn't understand this at first, after some thought it kind of makes sense that if you have a student fluctuating wildly you will get a more accurate picture of what he deserves.

For example, if a student gets 100/100 on a test, then 1/20 on a test, then 1/10... he would still have 102/130... or about 78%. By averaging the percentages, you actually get 38%. This is just a rough example, but kind of where she was heading with this. She does let her students know at the beginning of the year that small assignments hold as much merit as big ones this way, so it's fair... and the more i think about it, the better i feel about it.

If I were a student who got 78/100, 17/20 and 7/10 I would end up with an average of ~78%. If another student had the example above - i'd be pissed that we're in the same category just because he had one good test. Conversly, I would be pissed if 1 bad larger test threw my percentage away completely. (say 30/100, 10/10 and 20/20...)

But alas, it's not my decision either way... i'm just helping design something that'll help her get through the year a little easier haha =)

cheers
JPeG