Is Ken Ring saying, or is he not, that everyone should get out of Canterbury on 20 March? Why don't any scientists agree with him? If there's no quake, should we say he was wrong? He predicts so many that he gets a few right (the odds are he'll get about 30% right, as he's predicting so many); beforehand he says they are not predictions, merely opinions. After the fact, if a quake occurs, he claims he predicted it; if it does not, he falls back on saying they were just opinions. If we left town every time he said there'd be a quake we'd only be in town three out of four weeks a month.
Read the quoted authors below; they explain it way better than I ever could. Then forward this on to your friends.
If you want to go straight to the sources, here they are:
Dr Mark Quigley
Disclaimer: I have only copied and pasted the text below in case if I just posted the links, people couldn't be bothered clicking on them. If you are the author of either and are offended, I will remove the quoted text. I just want people to read what you've written.