Hi On Sun, 10 Mar 2002, Harry Avis wrote: > I have been asked by the VP to look at the validity of the screening tests > used by the English and Math Departments.
No matter what statistics you use, it would be important to consider restriction of range if only certain people are selected on the basis of their test scores, and if you are focussing on grades in the courses for which the tests were designed. If everyone omitted, than not an issue. What would be an issue then, however, would be what to do with dropouts? Assign them a grade of F or 0? Look separatedly at dropouts (categorical) and grades (quantitative). Assuming the above issues are dealt with, numerous ways to analyze the results. The one I would opt for is probably to translate the letter grades into numerical equivalents (perhaps the same ones used to calculate gpas at your institution?) and then use these grade scores as criterion variables with the tests scores as predictors. Do scattergrams to look for outliers and non-linearities. Calculate rs, regression lines, and significance, for predictors separately or in combination. If non-linearities, then one approach would be to enter squared predictors as well (although you might lose some non-statistics types here, but less so, I think, than transforming the variables). The general idea is to look at the > scores on the two tests and see how well they predict subsequent grades. > Another task would be to compare the grades students get in English 1A with > the grades they get in English A e.g. what percentage of student who get an > C in IA pass English A. I know I can do sorting for Grades in A by Grades in > 1A and get Chi squares with any of my stats programs. My question is, > however, What test of correlation do I use to compare a numerical score on a > test to a letter grade? Would I be better off converting numerical scores > into quintiles? I am somewhat vague about the details but I know that ties > affect correlations. By using either method I will end up with a lot of ties > in the since the range of grades is only 1-5. I would appreciate a reference > to the authority on whatever method you suggest because I know the math > department will be livid with rage that I am doing this. The psych > department got into a knockdown dragout ugly battle with the math folk over > our offering a stats class in the psych curriculum. The head honcho stats > guy stated flatly that psychologists don't know how to use statistics, teach > statistics or interpret stats. A couple of them still won't talk to us! > > > > Harry Avis PhD > Sierra College > Rocklin, CA 95677 > email: [EMAIL PROTECTED] > > Life is opinion - Marcus Aurelius > There is nothing that is good or bad, but that thinking makes it so - > Shakespeare > > > _________________________________________________________________ > Send and receive Hotmail on your mobile device: http://mobile.msn.com > > > --- > You are currently subscribed to tips as: [EMAIL PROTECTED] > To unsubscribe send a blank email to [EMAIL PROTECTED] > Best wishes Jim ============================================================================ James M. Clark (204) 786-9757 Department of Psychology (204) 774-4134 Fax University of Winnipeg 4L05D Winnipeg, Manitoba R3B 2E9 [EMAIL PROTECTED] CANADA http://www.uwinnipeg.ca/~clark ============================================================================ --- You are currently subscribed to tips as: [EMAIL PROTECTED] To unsubscribe send a blank email to [EMAIL PROTECTED]
