iteman ... one classical test analysis program ... allows top/bottom 27% split in it's item analysis routines (this is just one choice ... ) ...

i am amazed that any program would still do this ...

http://www.assess.com/Software/iteman.htm

At 04:58 PM 1/31/03 -0500, William B. Ware wrote:
Karl,

Are you thinking about the "Kelly split?" In doing item analysis, Kelly
recommended using the bottom 27% and top 27% of the cases. This
simplified the computation (by hand) without sacrificing very much
information. I think that the original reference might have been in the
1930s...

Bill

__________________________________________________________________________
William B. Ware, Professor Educational Psychology,
CB# 3500 Measurement, and Evaluation
University of North Carolina PHONE (919)-962-7848
Chapel Hill, NC 27599-3500 FAX: (919)-962-1533
http://www.unc.edu/~wbware/ EMAIL: [EMAIL PROTECTED]
__________________________________________________________________________


On Fri, 31 Jan 2003, Wuensch, Karl L wrote:

> When interested in the relationship between two continuous
> variables, some researchers will dichotomize one of them prior to analysis.
> I generally discourage such dichotomization, but the practice is common. A
> colleague asked me today about the practice of dichotomizing by a median
> split (top half versus bottom half) versus the practice of using only the
> tails (bottom third versus top third, for example). I outlined my thoughts
> on this matter and noted that I vaguely recall having read an article or two
> on this matter long ago, but cannot put my finger on the article(s). Can
> any of you all?
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Karl L. Wuensch, Department of Psychology,
> East Carolina University, Greenville NC 27858-4353
> Voice: 252-328-4102 Fax: 252-328-6283
> mailto:[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
> http://core.ecu.edu/psyc/wuenschk/klw.htm
> <http://core.ecu.edu/psyc/wuenschk/klw.htm>
>
> .
> .
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