"From early on his career, Ron Clarke collaborated with Derek Cornish on a controlled trial, which later led to their collaboration on rational choice theory. Did they consider their early controlled trial research to be a success or failure"

They considered it to be a success because had it been it was a failure they would not have come together for the rational choice theory.

Explanation:

controlled Trail:" is a study in which people are allocated at random (by chance alone) to receive one of several clinical interventions".

Rational Choice theory: "Rational choice theory assumes that individuals are rational actors using rational information to try to actively maximize their advantage in any situation and therefore consistently trying to minimize their losses"

the answer would be in this answer. someone already asked the question.  

where are the choices