Of course missing and zero are different... but what I meant was that if you failed to take a test, it was treated as 'zero', not 'missing'. :)

I'll guess 'the length parameter in POKELONG' (40, not 80) as the location of your error, by the way. :)

-Joe

On Mon, Apr 20, 2009 at 10:59 AM, Chang Chung <chang_y_chung@hotmail.com>wrote:

> On Mon, 20 Apr 2009 10:40:48 -0500, Joe Matise <snoopy369@GMAIL.COM> > wrote: > > >Maybe things have changed since I went to school, but a missing value for > a > >test score was a 'zero' back in the day... :) I'd either transform the > >missings to zero (if you have actual missing in the data) or do sum(of > >q3-q5)/3 ... > > > hi, Joe, > > in terms of data processing, a missing and a zero are totally different > things. Maybe teachers back then didn't have the sophisticated software > system like sas to make such a fine distinction. :-) > > by the way, I hard-coded "5" all over the place and made one mistake(guess > where?). that's not good. here is a parameterized and corrected one. :-) > > cheers, > chang > > /* test data. dot means the quiz missed. */ > data one; > input name $ q1-q5; > cards; > Alex 1 2 3 4 5 > Betty 2 2 . 4 4 > Clare 5 4 . . . > David 5 4 3 2 1 > ; > run; > > /* calculate mean quiz scores based on the > number of quizes taken, after dropping > two lowest scores. missing is considered > as the lowest score. */ > %let maxq = 5; /* change this to 12 if you have q1-q12 */ > %let mlen = %eval(&maxq. * 8); > data two; > set one; > /* make a copy */ > array q[1:&maxq.] 8 q1-q&maxq.; > array t[1:&maxq.] 8 _temporary_; > call poke(put(peekc(addr(q[1]),&mlen.),$&mlen..),addr(t[1]),&mlen.); > /* remove lowest two */ > call sortn(of t[*]); > call missing(t[1], t[2]); > /* calc n and mean */ > n = n(of t[*]); > mean = mean(of t[*]); > run; > > /* report */ > proc print data=two noobs; > run; > /* on lst > name q1 q2 q3 q4 q5 n mean > > Alex 1 2 3 4 5 3 4.00000 > Betty 2 2 . 4 4 3 3.33333 > Clare 5 4 . . . 2 4.50000 > David 5 4 3 2 1 3 4.00000 > */ >