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RE: st: RE: survey completion "flag"


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   RE: st: RE: survey completion "flag"
Date   Fri, 18 Feb 2005 17:01:41 -0000

The second problem is well identified. 
Thanks. 

The first problem is no problem. 

max(42, .) is 42, so initialising to 
missing is safe. 

This perhaps surprising feature can 
be rationalised as follows. Given 
arguments of 

-1, 0, 1, 2.71828, 3.14159, 42, . 

would you really want a -max()- function 
to return missing? It depends on the problem, 
but it can be forced the other way: 

gen max = <safe value> 
foreach v of local varlist { 
	replace max = cond(`v' == ., ., max(`v', `max')) if !mi(max) 
} 

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

Nick Winter

> Two problems, I think.
> 
> First, because whichislast is initialized as missing, 
> max(whichislast, `i') 
> will always return missing.
> 
> Second, if the variables numbers have leading zeros (e.g. 
> Q001 rather than 
> Q1), this code won't work.
> 
> Here's a version that also makes the resulting variable 
> contain the whole 
> variable name, not just the number:
> 
> gen str whichislast = ""
> qui forval i = 1/170 {
>          local j : di %03.0f `i'
>          replace whichislast = "Q`j'" if Q`j'<.
> }
 
> At 09:57 AM 2/18/2005 +0000, you wrote:
> >gen whichislast = .
> >qui forval i = 1/170 {
> >         replace whichislast = max(whichislast, `i') if Q`i' < .
> >}
> >
> >Nick
> >n.j.cox@durham.ac.uk
> >
> >Marilyn Matevia
> >
> > > Let me push my luck a little...  If this is the right way to write
> > > the code (to evaluate which of 170 questions is the last question
> > > answered):
> > >
> > > egen LASTRSP = rlast(Q001-Q170)
> > >
> > > ... Is there a way to have it return the variable name 
> (which is the
> > > question number) instead of the value of the response?
> >
> > > > Have a look at -egen, rlast()-.
> >
> > > > > I am a very new user of Stata, so I apologize in 
> advance if this
> > > is
> > > > > a dumb question.  I'm still learning how Stata "thinks"
> > > (compared to
> > > > > SAS) and can't figure out how to tackle this:
> > > > >
> > > > > I have a data set of responses to a very long (170 questions)
> > > survey
> > > > > with many nested skip patterns, and about 2200 respondents.
> > > After
> > > > > working out the skip codes, I still have many "missing"
> > > observations
> > > > > for some items, and figure these are due to 
> incomplete surveys.
> > > I
> > > > > want to create some kind of "completion flag" to see which
> > > > > respondents make it to the end of the survey, and - if they
> > > don't -
> > > > > to see which question is the respondent's last (which is
> > > complicated
> > > > > by the skip patterns).
> > > > >
> > > > > I'm just not coming up with a sensible way to do this 
> in Stata.
> > > Can
> > > > > someone point me in the right direction?

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