In house or outsource: A request for input

To run in house or outsource? At some banks this is a religious question. At others it is not even a question at all. Finally at some it is an ongoing debate. Celent hopes to write a report about this topic analyzing data across a wide range of US banks. The questions we ask? What are the key drivers for a lower efficiency ratio? Does outsourcing help more at a smaller bank or a bigger bank? Does outsourcing work better at a retail oriented bank or a business oriented bank? Is there any connection at all between efficiency ratio and the model under which the bank deploys its IT infrastructure? This is a genuine question and we will explore the answers with hard data and rigorous data analysis. Are there other questions around this topic that should be posed? I am actively seeking suggestions.