We are bad at making decisions. According to science, our decisions are based on oversimplification, laziness and prejudice. And that's assuming that we haven't already been hijacked by our surroundings or led astray by our subconscious. We often allow emotions take control of decision making and disable our logic.
Here is a formula used to decide whether or not you should buy something:
http://www.bbc.co.uk/sn/tvradio/prog...ions/buy.shtml
....[BBC Horizon Documentary] - How to make Better Decisions, good watch