Banks certainly have very accurate info about investments they have made by firm type and maturity as well as the interest rates and other charges. You will probably need to so a survey to find these out. Commercial banks in general have a preference for loans of short maturity. If you can find out from the banks their investments by maturity, it is easy to find out their bias.
Assalamu alaikum Sir, I am very happy to get a reply from you, I was your student in University of Dhaka for a brief time. You took a few macroeconomics classes in our second year of study, Madam later on took over the course. We read your book in that course, not to sound like a sycophant but I thoroughly enjoyed your book.
I am trying to write a research proposal for PhD and my interested area is investment portfolio of banks. Can you suggest any model/ formula to measure biasness in banks investment portfolio?
Nice to know you are planning to write a Ph.D. dissertation. I suggest that you do a thorough review of the literature on the topic. That should give you some idea regarding how to proceed. It will not be very productive to work hard to devise a model on bias only to find later that the literature already has better options. By the way which university are you planning to register with for Ph.D. ?