Re: st: different handling if missings in programs using syntax varlist [if}

[Bjorn Van Campenhout <bjorn.vancampenhout@gmail.com>]

Thanks Nick, for explaining the logic behind this apparent difference in 
behaviour:

> I see no puzzle here. In your -foo-, the variable -comment- was
> created without reference to -price-. In fact, the rest of the program
> had no bearing on that. So, no values were missing.

> In -foobar-, things were different. Observation with missing -price-
> were excluded.

Thanks Daniel, for pointing out the option -novarlist- to -marksample-, where it clearly states:
	
	You should also specify novarlist when missing values are not to cause
        observations to be excluded (perhaps you are analyzing the pattern of missing
        values).


It now works as I 'expected':

sysuse auto

replace price=. if foreign==1

cap pro drop foo
pro def foo
  syntax varlist
  gen comment="this is only a test"
end



cap pro drop foobar
pro def foobar
  syntax varlist [if]
  marksample touse, novarlist
  gen comment="this is only a test" if `touse'
end

foo price
drop comment
foobar price

Thanks,
Bjorn



On 04/22/2011 10:39 AM, Nick Cox wrote:
> Also -nmissing- (SJ).
>
> Nick
>
> On Fri, Apr 22, 2011 at 9:24 AM, daniel klein
> <klein.daniel.81@googlemail.com>  wrote:
> > By the way, regarding your plan to write a program reporting on
> > missings, you might want to take a look at -help misstable- if you are
> > not yet aware of this program.
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