Why is applied research often conducted outside a formal laboratory, whereas theoretical research generally takes place in a laboratory?

What will be an ideal response?

Applied research very often answers a specific question about behaviors in a natural setting. As such, it may be important to study behaviors in the environments in which they typically occur, rather than in a restricted and somewhat artificial atmosphere of the lab.
On the other hand, in theoretical research, investigators are frequently interested in the effect of a variable that has a consistent, but small, effect on behavior. In such a situation, it makes sense to eliminate variables that have big effects on behavior that will obscure the effects of variables that have smaller effects. One way to get rid of the larger effects of variables you aren't interested in is to control the environment very carefully, which is easiest to do in a lab.