Thanks @Mudit.Kushalvardhan for bringing this excellent question. I am reading this on other thread as well. There are statistical calculations and I think @Navin_J & @ChaitanyaC have covered possible solutions & pointers on number crunching, I agree with them.
But, your point around : “i am clearly talking from point of view of returns and comparing it with other alternative arrangements to know if we are doing better job than them…so we can keep doing it” is very difficult one.
There was an interesting observation from @Chandragupta where he says: “Note that even the performances of two fund managers may not be exactly comparable” I would like to emphasize on this point more not because of individual capability/skill but because of the nature of markets.
For me personally, making X% more than Nifty50 is a satisfying performance & X% less than Nift50 is a learning factor and even this may not be right process. I think, this is because of unknown luck factor. Shortly, I would like to present next model skill vs luck around this scenario.