Many bosses don’t have exact work standards. That is too bad. I pay commission, so if you make poor commissions, then I know that something is wrong! That is easy! Some jobs are harder to assess than others in terms of performance. As a boss, it is your job to figure out how well your people should be doing at various levels of experience. If they don’t meet the mark, then get rid of them.
If you don’t train people adequately, then it is YOU who is to blame if you have good workers who don’t perform. People need interaction with their managers other than yelling sessions. Your job is to TEACH, not to yell. Yelling comes after a generous period of nurturing where the worker just won’t cooperate no matter what. Honestly, you should fire anyone you have to regularly yell at unless you only have to yell at them about a particular detail.
Yelling is a last recourse. In India people get an ego trip for yelling at their inferiors. The concept of inferiority is huge in India by the way. Sometimes, you can not get good workers, so you have to settle for nitwits who benefit from being yelled at. Choose carefully who you yell at. For some it is actually constructive, and for others, you just upset them!