Stata The Stata listserver
[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]

RE: st: Re: grading


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   RE: st: Re: grading
Date   Tue, 10 Jun 2003 19:38:15 +0100

Christopher W. Ryan

> > Thanks.  I must still not understand how -pctile- and
> > -xtile- work.  This code
> > gave me sort of a U-shaped distribution of grades:
> > highest-scoring students
> > got fail, and so did the lowest-scoring.  In the middle
> > were honors, high pass,
> > and pass.
> >
> > I tried this (adding in a "conditional" grade which I
> > forgot to mention) :
> >
> > use "C:\quarantine\studentprogress.dta"
> > collapse (sum) pointsearned, by(studentid)
> > gsort -pointsearned
> > list
> > gen str10 finalgrade="pass"
> > replace finalgrade="honors" if _n<=(.15*_N)
> > replace finalgrade="high pass" if _n>(.15*_N) & _n<=(.25*_N)
> > replace finalgrade="conditional" if  pointsearned<300 &
> > pointsearned>199
> > replace finalgrade="fail" if pointsearned<200
> > list
> >
> > Clumsier, but it seemed to work.
>
> Dangerous code.
>
> This could give students different final grades
> even though they got the same points earned,
> because you could be splitting ties quite
> arbitrarily!

To show the point, I graded those cars:

sysuse auto, clear
gsort -mpg
gen str10 finalgrade="pass"
replace finalgrade="honors" if _n<=(.15*_N)
replace finalgrade="high pass" if _n>(.15*_N) & _n<=(.25*_N)
replace finalgrade="conditional" if mpg<15 &  mpg>13
replace finalgrade="fail" if mpg<13

The last two lines are immaterial, so long as the thresholds lie below
the upper quartile.

This was the first and only example I tried, and there is
one "student" (car) with 25 mpg who should be filing an appeal.

Nick
n.j.cox@durham.ac.uk

*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/



© Copyright 1996–2014 StataCorp LP   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index