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st: RE: Easy question: How to get 0 to show up?


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: Easy question: How to get 0 to show up?
Date   Fri, 23 Jun 2006 10:06:44 +0100

I can't speak for STATA. Curiously enough, 
the same question arises in Stata. 

The key question is how you expect Stata to 
know that "Green" was also a possible category. 

I guess that there are some languages in which
the fact that "Green" was 
defined as a possible value by way of a specification 
of possible values would be enough. 

Stata doesn't work that way, however. Even if 
you define a set of value labels, Stata doesn't 
automatically tabulate those which are not 
represented in the data, or the subset of the 
data you specify. If these data are string, 
then why should Stata know that "Green" was 
a possible answer any more than (say) "Aardvark"?

So you need a work-around in which you yourself spell 
out the possible values. The only ones I know
are -tabcount- from SSC and the earlier -tabcond-
from SSC. Note that had you used 

. findit zeros 

or 

. findit zero 

you would have found out about -tabcount- for 
yourself (together, naturally, with lots of 
other stuff). 

. findit tabulate zero 

would have zeroed in further on what you need. 

Here are a few simple examples of how -tabcount- 
works: 

. tabcount foreign, v(0 1 2 3 4)

----------------------
 Car type |      Freq.
----------+-----------
 Domestic |         52
  Foreign |         22
        2 |           
        3 |           
        4 |           
----------------------

. tabcount foreign, v(0 1 2 3 4) zero

----------------------
 Car type |      Freq.
----------+-----------
 Domestic |         52
  Foreign |         22
        2 |          0
        3 |          0
        4 |          0
----------------------

. decode foreign, gen(FOREIGN)

. tabcount FOREIGN , v("Domestic" "Foreign" "Martian" "Venusian") zero

----------------------
 Car type |      Freq.
----------+-----------
 Domestic |         52
  Foreign |         22
  Martian |          0
 Venusian |          0
----------------------

Missings are not shown by default. I guess the reason 
you have a puzzle about missing is that you think string 
"." means missing. With strings in Stata only the empty string 
"" means missing. If you have strings "." that you 
regard as missing you should just exclude those if desired 
by 

... if COLOR != "." 

or replace them with empty strings. 

There was a more discursive account in the Stata Journal  

SJ-3-4  pr0011  . . . . . . . .  Speaking Stata: Problems with tables, Part II
        Q4/03   SJ 3(4):420--439                             
        reviews three user-written commands (tabcount, makematrix,
        and groups) as different approaches to tabulation problems

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

buddyb
 
> I'm running STATA 8.
> 
> If I had a multiple choice question, like, what is
> your favorite color with red, yellow, black, green as
> the given choices,and asked 7 people and got the
> following results....
> 
> Red     1
> Yellow  2
> Black   3
> Green   0
>          . (missing)
> 
> When I do a Table COLOR (this is my vname),
> I get:
> 
> Red    1
> Yellow 2
> Black  3
> 
> The Green does not show up and I would like it too. I
> want to repress the missing.  How do I do this? 
 

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