Generate new variable if meets conditions from 3 or 4 other variables

[Yedidya Saiman]

I have 4 binary variables (0/1) and trying to create a newvar=1 if any 3 of those 4 variables ==1 and 0 if not.
I can write it with a lot of if statements, but can't figure an easier way which I am sure exists

Thanks

[Alan Neustadtl]

Assuming that you do not have any missing values, how about something like this untested code:

tempvar flag
gen flag=(v1+v2+v3+v4)
generate newvar=0
replace newvar=1 if `flag'==1

[Bruce Weaver]

Here's a method that should work even if you have missing values.

* Generate some data to illustrate
clear *
input byte(v1 v2 v3 v4)
. . . .
0 0 0 0
1 1 1 1
end
fillin v1 v2 v3 v4
drop _fillin

egen byte rowsum = rowtotal(v1-v4)
generate byte flag = rowsum > 2
list if flag==1

Output from the list command:

. list if flag==1

     +-----------------------------------+
     | v1   v2   v3   v4   rowsum   flag |
     |-----------------------------------|
 14. |  0    1    1    1        3      1 |
 32. |  1    0    1    1        3      1 |
 38. |  1    1    0    1        3      1 |
 40. |  1    1    1    0        3      1 |
 41. |  1    1    1    1        4      1 |
     |-----------------------------------|
 42. |  1    1    1    .        3      1 |
 44. |  1    1    .    1        3      1 |
 50. |  1    .    1    1        3      1 |
 68. |  .    1    1    1        3      1 |
     +-----------------------------------+

[Yedidya Saiman]

thanks so much - worked beautifully!