Trouble creating new variable from existing variables

[Judy Bramble]

I'm new to Stata but familiar with stat programs I thought this would be easy. I'm trying to create a new variable (G02) which takes on the value of another variable (Obs) if a third variable's condition (Gap) is met. I tried to do this when the third variable was a string variable and got an error: type mismatch so I changed the third variable so that all were numeric and I still get an error - invalid syntax.

generate G02 = Obs if Gap=2
invalid syntax
r(198);

I did it again with generate G02 = . and then replacing G02 using the same if statement and got the same invalid syntax issue.

I need to break down Gap into a bunch of new variables depending on the value of Gap. Why can't I make this work? Thanks for you help.

[Judy Bramble]

Never mind, figured it out. Stata apparently doesn't like just an = sign. It works with: generate G02=Obs if (Gap>=2) & (Gap<3)

[Clyde Schechter]

In Stata, as in many other programming languages, you have to distinguish between the assignment operator (=) and the equality relation (==). They are not interchangeable. You need

gen G02 = Obs if Gap == 2

Added: Crossed with #2. Your solution will work provided Gap is an integer. But if you try the same kind of thing with a variable that is floating point, it will fail. Just use the == operator to refer to the equality relation.

[Judy Bramble]

That's great, and much better than what I was doing to make it work, thank you!