Virtually impossible to track. What I have done before getting a notable prize:
a. Screenshot of stats before the prize
b. Screen shot of the prize
c. Screen shot of stats post the prize
In this case, I also took screenshot of the stats one hour after the bonus is reflected in my individual bonus section. By toggling between these screen shots, the issue becomes obvious.
I do this only for notable prizes so 'minor bonuses' like 2% increase and like are not tracked. I have no way of knowing if they are effective. 20:80 rule applies.