How we change what others think, feel, believe and do
When criticism is needed, do not avoid it, although you should pick your moment. It is often not a good idea to criticize another person in public (unless there is a particular reason for doing so.
When you are going to criticize someone else, first make sure that your motivations are genuine. Do not criticize to gain points or otherwise profit from the other person.
Be very specific about the things you are criticizing. Describe the action and the cause-and-effect relationship with the outcomes, saying 'when you did that, then this happened'.
Criticize the action, but not the person. Rather than say 'you are wrong' say 'what you did was wrong'.
Seek to neither criticize too much at once nor criticize too often. Make the criticism as easy as possible to accept.
Check that they understand the criticism and accept it as positive support.
Discuss what happens next, helping them to see the way forward and to avoid future criticism. If necessary, describe the consequences of repeated failure.
Your report was not handed in on time last week. That led to me looking really stupid in the board meeting.
When you left the door unlocked there was a serious risk of us being burgled. How can we ensure that it will not happen again?
I am not happy about the time you are taking off for lunch. You were late for two afternoon meetings last week.
If you criticize a person, then you are attacking their sense of identity, which is a fundamental part of who they are. This is highly likely to provoke a fight-or-flight reaction, and unlikely for them to carefully consider and accept the criticism.
Avoiding criticism of another person may well be doing them a disservice. If you do not point out their problems, then they are probably doomed to repeat history.
Frequent or multiple criticism may lead to people feeling persecuted, with the result that feel overwhelmed and unwilling or unable to improve
Remember that the goal of criticism should always be to help the other person improve. It should never be about revenge or punishment. Being assertive does not mean being a judge, jury or executioner.