Stata 11 help for cond() help cond() ------------------------------------------------------------------------------- Title [D] functions -- Functions Programming function cond(x,a,b,c) or cond(x,a,b) Domain x: -8e+307 to 8e+307 and missing; 0 means false, otherwise interpreted as true Domain a: numbers and strings Domain b: numbers if a is a number; strings if a is a string Domain c: numbers if a is a number; strings if a is a string Range: a, b, and c Description: returns a if x is true and nonmissing, b if x is false, and c if x is missing. returns a if c is not specified and x evaluates to missing. note that expressions such as x>2 will never evaluate to missing. cond(x>2,50,70) returns 50 if x > 2 (includes x > .) cond(x>2,50,70) returns 70 if x < 2 If you need a case for missing values in the above examples, try cond(missing(x), ., cond(x>2,50,70)) returns . if x is missing, returns 50 if x > 2, and returns 70 if x<2 If the first argument is a scalar that may contain a missing value or a variable containing missing values, the fourth argument has an effect. cond(wage,1,0,.) returns 1 if wage is not zero and not missing. cond(wage,1,0,.) returns 0 if wage is zero. cond(wage,1,0,.) returns . if wage is missing. Caution: If the first argument to cond() is a logical expression, i.e., cond(x>2,50,70,.), the fourth argument is never reached. Also see Manual: [D] functions Help: [D] functions, [D] functions (programming functions), [U] 11.1.3 if exp, [P] if