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Re: st: RE: help with encode


From   Miranda Kim <mk@mrc.soton.ac.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: RE: help with encode
Date   Fri, 24 Jul 2009 12:28:01 +0100

Thank you for your input. As you say, there are many different ways to make this work and so I have bypassed using encode. I am grateful for the many suggestions, and I apologize if my initial question was not laid out clearly enough.
Many thanks,
Miranda
ps: here is what I got trying to use encode:
. tab1 fish

-> tabulation of fish
      fish |      Freq.     Percent        Cum.
------------+-----------------------------------
         C |         56       50.45       50.45
         S |         55       49.55      100.00
------------+-----------------------------------
     Total |        111      100.00

. desc fish

             storage  display     value
variable name   type   format      label      variable label
--------------------------------------------------------------------------------------
fish str1 %1s
. label def fish 0 "Control" 1 "Salmon"

. encode fish, gen(fish1) label(fish)

. tab1 fish1, nolabel

-> tabulation of fish1
     fish1 |      Freq.     Percent        Cum.
------------+-----------------------------------
         2 |         56       50.45       50.45
         3 |         55       49.55      100.00
------------+-----------------------------------
     Total |        111      100.00

Michael Hanson wrote:
If that really is the situation you're in -- all encoded values are 2's and 3's -- then why not simply linearly transform the encoded variables to the values that you want? That is, type:

replace gender = gender - 2

(Subtract 1 if you had 1's and 2's as mentioned in your original post.)

However, I suspect something else is going on. My expectation is that you have more than just two string values ("m" and "f") in your series. Can you provide to the list the output of -table female-? I suspect that if you try Nick's -tab ...- command shown below, you would also find unexpected values.

However, these are all conjectures. You would likely resolve your situation much more quickly (and waste fewer people's time on the list in the process) if you followed the guidance clearly laid out in the Statalist FAQ:

3.3 Stata references in your question
Say exactly what you typed and exactly what Stata typed (or did) in response. N.B. exactly!

Why not at least show us what actually happened? In this case, copy and paste from the results window the *exact* -encode- command and resulting Stata output. Then copy and past whatever command led you to conclude that you were getting 2's and 3's, and the *exact* and *complete* output from that command. (In consideration to Statalist readers, please don't provide us with a lengthy -list- output. Use -table- instead, as suggested above.)

Hope this helps,
Mike


On Jul 24, 2009, at 4:09 AM, Miranda Kim wrote:

I tried this but couldn't make it work, as it then automatically encodes the variables with 2's and 3's...

Nick Cox wrote:
In addition to other answers the direct answer to the second question is
"Yes":
label def female 0 "m" 1 "f" encode gender, gen(female) label(female)

It would no harm to check on any missings:
tab gender if !inlist(female, 0, 1)
Nick n.j.cox@durham.ac.uk
Miranda Kim

How can I efficiently convert string variables (such as gender with values 'f' 'm') into binary 0/1 variables?
Can I fiddle with encode so that it codes 0/1 instead of 1/2?
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