# Testing for mean difference in 3 subjects for a group of students

I am sorry if this is a naive question, but I wanted to have your suggestions before considering anything. Suppose I have a group of "n" students and I have their score in three courses: A, B, and C. If the scores are not on the same scale, I can standardize them before comparison. For comparing the mean difference between two courses I could have done the Paired-T test, but I am not sure about the extension of paired T-test for comparing more than two means for dependent data. Any ideas? Thanks in advance!

• Try the two-way ANOVA. Testing three paired-T test is not appropriate here.
– xjf
Feb 2, 2017 at 22:46
• If you standardize the grades within course, all courses will have a mean of zero. Obviously, then, there will no difference between courses in mean score. Feb 3, 2017 at 0:28
• @Jianfeng Could you please explain what will be the factors for two-way ANOVA? Feb 3, 2017 at 15:29
• @JoelW. Thank you for pointing that out. By standardize I meant I will convert all the scores under the same scale (eg. score out of 100) Feb 3, 2017 at 15:31
• @curiousmind, one factor is course and the other factor is student, since the scores from the same student are correlated.
– xjf
Feb 3, 2017 at 16:29