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st: Re: grading
On Wednesday, June 11, 2003, at 02:33 AM, Chris wrote:
Thanks. I must still not understand how -pctile- and -xtile- work.
This codeI had the percentiles backward, given that the lowest percentiles will
be the lowest grades.
gave me sort of a U-shaped distribution of grades: highest-scoring
got fail, and so did the lowest-scoring. In the middle were honors,
The 'gr' variable contains 20 observations, corresponding to the 5th,
10th, 15th,... 95th
pctile gr = score, nq(20)
xtile pc = score, cut(gr)
g str9 grade="Fail"
replace grade="Honors" if pc>17
replace grade="High Pass" if pc>12 & pc<18
replace grade="Pass" if grade=="Fail" & score>299
percentiles of the distribution. Thus the top 3 categories should be
pc=18, 19, 20; the next five should be 13,..17.
The example you posted today contained rules not included in your
original postiing (re 199, e.g.)
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