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From | Nick Cox <njcoxstata@gmail.com> |
To | statalist@hsphsun2.harvard.edu |
Subject | Re: st: Contract/Collapse Combination |
Date | Mon, 21 May 2012 23:51:13 +0100 |
This sounds to me like contract x* entercol Nick On Mon, May 21, 2012 at 9:45 PM, Lucas <lucaselastic@gmail.com> wrote: > So, I am attempting to construct a file containing a list-format 15 > (or so) -way crosstab, with frequencies of cases for each combination > of values. I have millions of cases, so this crosstab is appropriate. > > What would be ideal would be the ability to use the contract command > but, instead of only indicating the need for one count, could ask for > the sum of two variables. Assume I have a dichotomous variable (say, > "enter college). Those who enter college are coded 1, those who do > not are coded zero. I could then construct a new variable, named > "DidNotEnter", coded 1 for those who do NOT enter college, and zero > for those who do. > > If I could then write something like: > > collapse x1 x2 x3 x4 ... xj, freq(EnterCol) freq(DidNotEnter) zero > > I could get the totals needed. The plan is to speed processing of a > computationally difficult model by substituting a model of counts for a > model of individual cases. To do this I need the total count of each > combination and the count meeting the condition (e.g., entering college). > My code above would, if possible, produce a file that allowed me to > add the two frequencies to get the total. > > As far as I can tell, this is not possible. What seems to be required > is to run it with only the "Enter College" freq, then somehow break > the two cases (EnterCollege=1 vs. EnterCollege=0) (or, alternatively, > to keep EC==1 and run it, and then re-run with EC==0) and somehow > combine them, an operation that seems to be begging for error in > matching. * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/