if command with 3 conditions

[Amaranta Losey]

I am trying to generate a new variable using the "if" command based on 3 other variables
ex:
gen completetx=1 if (neo==1 & surgery==1 & adjuvant==1)

However, it seems that stata only reads the first 2 conditions, and ignores the third. Am I doing something wrong? Is it possible to have more than 2 conditions with an if command? Thanks!

[Joseph Coveney]

it seems that stata only reads the first 2 conditions, and ignores the third.

I can't replicate your problem.

.ÿversionÿ16.1

.ÿclearÿ*

.ÿquietlyÿsetÿobsÿ6

.ÿgenerateÿbyteÿneoÿ=ÿ_nÿ>=ÿ_Nÿ/ÿ2

.ÿgenerateÿbyteÿsurgeryÿ=ÿmod(_n,ÿ2)

.ÿsortÿsurgeryÿneo

.ÿgenerateÿbyteÿadjuvantÿ=ÿmod(_n,ÿ2)

.ÿgenerateÿbyteÿcompletetxÿ=ÿ1ÿifÿ(neo==1ÿ&ÿsurgery==1ÿ&ÿadjuvant==1)
(5ÿmissingÿvaluesÿgenerated)

.ÿlistÿifÿneoÿ&ÿsurgery,ÿnoobsÿabbreviate(20)

ÿÿ+---------------------------------------+
ÿÿ|ÿneoÿÿÿsurgeryÿÿÿadjuvantÿÿÿcompletetxÿ|
ÿÿ|---------------------------------------|
ÿÿ|ÿÿÿ1ÿÿÿÿÿÿÿÿÿ1ÿÿÿÿÿÿÿÿÿÿ1ÿÿÿÿÿÿÿÿÿÿÿÿ1ÿ|
ÿÿ|ÿÿÿ1ÿÿÿÿÿÿÿÿÿ1ÿÿÿÿÿÿÿÿÿÿ0ÿÿÿÿÿÿÿÿÿÿÿÿ.ÿ|
ÿÿ+---------------------------------------+

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[Nick Cox]

I agree with Joseph Coveney. Your syntax looks fine. If the three variables are all (0, 1) then a programmer's trick like this is a little tempting

if neo & adjuvant & surgery

but it is blown by missing values. So, your syntax looks fine.

[William Lisowski]

If three variables can each take values 1, 0 (or something else other than 1), or missing, then the 27 possible combinations and the result of applying the generate command are as follows.

. generate vall=1 if (v1==1 & v2==1 & v3==1)
(26 missing values generated)

. list, noobs sepby(v1 v2)

  +---------------------+
  | v1   v2   v3   vall |
  |---------------------|
  |  0    0    0      . |
  |  0    0    1      . |
  |  0    0    .      . |
  |---------------------|
  |  0    1    0      . |
  |  0    1    1      . |
  |  0    1    .      . |
  |---------------------|
  |  0    .    0      . |
  |  0    .    1      . |
  |  0    .    .      . |
  |---------------------|
  |  1    0    0      . |
  |  1    0    1      . |
  |  1    0    .      . |
  |---------------------|
  |  1    1    0      . |
  |  1    1    1      1 |
  |  1    1    .      . |
  |---------------------|
  |  1    .    0      . |
  |  1    .    1      . |
  |  1    .    .      . |
  |---------------------|
  |  .    0    0      . |
  |  .    0    1      . |
  |  .    0    .      . |
  |---------------------|
  |  .    1    0      . |
  |  .    1    1      . |
  |  .    1    .      . |
  |---------------------|
  |  .    .    0      . |
  |  .    .    1      . |
  |  .    .    .      . |
  +---------------------+