generation a new variable using -cond()- function

[Saleh Babazadeh]

Hi,

I need to generate a variable which is combination of two variables. In our survey the question " Do you want more children?" has been asked from women and saved in the data set based on the pregnancy at the moment. So we ended up with the same question asked from women (Non-preganant and pregnant) in two variables. I need to combine these two variables in one variable regardless of variable of pregnancy. I wanted to use the function -cond()- that Nick Cox thought me here once, but I can't get the appropriate variable.
I know I can generate the new variable using gen and replace commands, but I wanted to learn to use -cond()- function in the future.

I appreciate your inputs.

* Example generated by -dataex-. To install: ssc install dataex
clear
input long(pregnant more_children more_children_pregnant)
  0   1   .
  0   1   .
  1   .   1
  0   3   .
  0   2   .
  0   1   .
  0   1   .
-88   1   .
  0   1   .
  0   1   .
  0   2   .
  0   2   .
  0   1   .
  0 -88   .
  1   .   1
  0   1   .
  0   1   .
  0   1   .
  0   1   .
  0   1   .
  0   1   .
  0   3   .
  0   2   .
  0   1   .
  0   1   .
  0   1   .
  0 -88   .
  0   1   .
  0   1   .
  0   2   .
  0   2   .
  0   3   .
  0   1   .
  0   1   .
  0   1   .
  0   1   .
  0   1   .
  0   2   .
  0 -88   .
  0   3   .
  0   1   .
  0   1   .
  1   .   1
  0   2   .
  0   2   .
  0 -88   .
  0   1   .
  0   1   .
  1   . -88
  0   1   .
  0 -88   .
  0   1   .
  0   1   .
  0   1   .
  0 -88   .
  0 -88   .
  0 -88   .
  0   1   .
  0   1   .
  0   1   .
-88   2   .
  1   .   1
  0   1   .
  0   2   .
  1   . -88
  0   2   .
  0   2   .
  0 -88   .
  0   1   .
  0   1   .
  0   2   .
  0   2   .
  0 -88   .
  1   . -88
  0   1   .
  0   3   .
  0   1   .
  0   1   .
  0   1   .
  0   1   .
  0   1   .
  0   1   .
  1   .   1
  0   1   .
  0   1   .
  0   1   .
  0   1   .
  0   2   .
  0   1   .
  0   1   .
  1   .   1
  0   1   .
  0   1   .
  0 -88   .
  0   2   .
  0   1   .
  0   1   .
  0   1   .
  1   .   2
  0   1   .
end
label values pregnant yesno
label def yesno -88 "-88", modify
label def yesno 0 "no", modify
label def yesno 1 "yes", modify
label values more_children morechildrenlist
label values more_children_pregnant morechildrenlist
label def morechildrenlist -88 "-88", modify
label def morechildrenlist 1 "have_child", modify
label def morechildrenlist 2 "no_children", modify
label def morechildrenlist 3 "infertile", modify

[Nick Cox]

-88 looks like some special code that you should map to an extended missing value. Otherwise your new variable could be max(,) or min(,) of the two variables as each function ignores missings when possible. cond(!missing(more_children), more_children, more_children_pregnant) is a way to do it with cond() but max(more_children, more_children_pregnant) is in my view better.

[William Lisowski]

While Nick's advice is good, and what I would code myself, since you gave good sample data using dataex, let me demonstrate how to use the cond() function and the pregnant variable to combine the two values into a single variable. Starting by running the code you provided, we continue with

generate more_children_all = cond(pregnant==1,more_children_pregnant,more_children)
label values more_children_all morechildrenlist

which gives us

. list, clean

       pregnant   more_chil~n   more_chil~t   more_chil~l  
  1.         no    have_child             .    have_child  
  2.         no    have_child             .    have_child  
  3.        yes             .    have_child    have_child  
  4.         no     infertile             .     infertile  
  5.         no   no_children             .   no_children  
  6.         no    have_child             .    have_child  
  7.         no    have_child             .    have_child  
  8.        -88    have_child             .    have_child  
  9.         no    have_child             .    have_child  
 10.         no    have_child             .    have_child  
 11.         no   no_children             .   no_children  
 12.         no   no_children             .   no_children  
 13.         no    have_child             .    have_child  
 14.         no           -88             .           -88  
 15.        yes             .    have_child    have_child  
 16.         no    have_child             .    have_child  
 17.         no    have_child             .    have_child  
 18.         no    have_child             .    have_child  
 19.         no    have_child             .    have_child  
 20.         no    have_child             .    have_child  
 21.         no    have_child             .    have_child  
 22.         no     infertile             .     infertile  
 23.         no   no_children             .   no_children  
 24.         no    have_child             .    have_child  
 25.         no    have_child             .    have_child  
 26.         no    have_child             .    have_child  
 27.         no           -88             .           -88  
 28.         no    have_child             .    have_child  
 29.         no    have_child             .    have_child  
 30.         no   no_children             .   no_children  
 31.         no   no_children             .   no_children  
 32.         no     infertile             .     infertile  
 33.         no    have_child             .    have_child  
 34.         no    have_child             .    have_child  
 35.         no    have_child             .    have_child  
 36.         no    have_child             .    have_child  
 37.         no    have_child             .    have_child  
 38.         no   no_children             .   no_children  
 39.         no           -88             .           -88  
 40.         no     infertile             .     infertile  
 41.         no    have_child             .    have_child  
 42.         no    have_child             .    have_child  
 43.        yes             .    have_child    have_child  
 44.         no   no_children             .   no_children  
 45.         no   no_children             .   no_children  
 46.         no           -88             .           -88  
 47.         no    have_child             .    have_child  
 48.         no    have_child             .    have_child  
 49.        yes             .           -88           -88  
 50.         no    have_child             .    have_child  
 51.         no           -88             .           -88  
 52.         no    have_child             .    have_child  
 53.         no    have_child             .    have_child  
 54.         no    have_child             .    have_child  
 55.         no           -88             .           -88  
 56.         no           -88             .           -88  
 57.         no           -88             .           -88  
 58.         no    have_child             .    have_child  
 59.         no    have_child             .    have_child  
 60.         no    have_child             .    have_child  
 61.        -88   no_children             .   no_children  
 62.        yes             .    have_child    have_child  
 63.         no    have_child             .    have_child  
 64.         no   no_children             .   no_children  
 65.        yes             .           -88           -88  
 66.         no   no_children             .   no_children  
 67.         no   no_children             .   no_children  
 68.         no           -88             .           -88  
 69.         no    have_child             .    have_child  
 70.         no    have_child             .    have_child  
 71.         no   no_children             .   no_children  
 72.         no   no_children             .   no_children  
 73.         no           -88             .           -88  
 74.        yes             .           -88           -88  
 75.         no    have_child             .    have_child  
 76.         no     infertile             .     infertile  
 77.         no    have_child             .    have_child  
 78.         no    have_child             .    have_child  
 79.         no    have_child             .    have_child  
 80.         no    have_child             .    have_child  
 81.         no    have_child             .    have_child  
 82.         no    have_child             .    have_child  
 83.        yes             .    have_child    have_child  
 84.         no    have_child             .    have_child  
 85.         no    have_child             .    have_child  
 86.         no    have_child             .    have_child  
 87.         no    have_child             .    have_child  
 88.         no   no_children             .   no_children  
 89.         no    have_child             .    have_child  
 90.         no    have_child             .    have_child  
 91.        yes             .    have_child    have_child  
 92.         no    have_child             .    have_child  
 93.         no    have_child             .    have_child  
 94.         no           -88             .           -88  
 95.         no   no_children             .   no_children  
 96.         no    have_child             .    have_child  
 97.         no    have_child             .    have_child  
 98.         no    have_child             .    have_child  
 99.        yes             .   no_children   no_children  
100.         no    have_child             .    have_child

[Saleh Babazadeh]

Thank you both. I appreciate your help.