Hi
On 12 Feb 2001, EAKIN MARK E wrote:
> I have just given a class their first exam and would like to put a class
> of 60 into groups of size three. I would like the groups to have basically
> the same average score on the first exam. Would anyone know of an
> algorithm for doing this?
Assuming you have access to some statistical package like SPSS,
do the following.
1. Seed the random number generator:
SET SEED RANDOM in SPSS
- note: RANDOM option does not work on Unix versions
2. Order the cases on the first exam:
SORT CASES score1
3. Create a blocking variable:
COMPUTE block = TRUNC(($CASENUM-1)/3)+1
block will have the values 1,1,1,2,2,2,3,3,3,...
4. Generate a random variate:
COMPUTE rand = uniform
5. Sort on block, rand:
SORT CASES block, rand
cases will be in random order within blocks of 3
6. Create a grouping variable:
COMPUTE group = MOD(($CASENUM-1),3)+1
Group will have the values 1,2,3,1,2,3,...
Group will contain scores with approximately equivalent averages,
as could be verified by ANOVA. Forming the groups might also be
done in DBase, a spreadsheet, or any language that could generate
random variates and sort, as long as the program allowed access
to something like $CASENUM (i.e., the current position of the
case/record in the file).
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
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