I have been asked by the VP to look at the validity of the screening tests 
used by the English and Math Departments. 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


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