Why you should never claim when being lynched.

[Zymf]

If you feel threatened enough to fear for your life, you should claim! Whether or not you should tell the truth or tell a lie is more complicated..

You should tell a lie if you are a powerfull role that it would be a great loss for the town if the mafia decided to kill you at night.
You might also want to tell a lie if you WANT the mafia to target you, for exampel when you have a useless role or can't be killed.
However, be carefull when telling a lie! If you claim a role, that someone else has, they might reveal your lie (which could be bad in more ways than 1)

Once you claim a role, you kind of make a promise with the town.. If you are unable to live up to your role, the other players will doubt you and lynch you.