Part I: Use the formula P=40 to 70, in which P stands for the probability of success and the number indicates the percentage of information acquired.
Part II: Once the information is in the 40 to 70 range, go with your gut.
One thing I learned in Iraq, "not making a decision, IS MAKING A DECISION." I actually saw people get hurt because leaders couldn't make up their mind. In fact, the lesson I really learned was that a bad decision is better than no decision. At least a bad decision can be corrected, no decision means that the opportunity passes you by.
And in today's age, you cannot wait for 100%. Where would Steve Jobs or Bill Gates be if they waited to be 100% sure? Apple and Microsoft wouldn't be what they are today. A leader needs to push boundaries, and go with his/her gut. If you are 40%+ sure you will succeed, it is time to move. Otherwise, the opportunity passes (or the world explodes around you).
The other side of "analysis paralysis" comes from information or choice overload. I recently had a new experience with this. I needed to update my cell phone and I kept putting off the decision. My old phone worked, and a better phone would be out in 6 months, what's the rush? Really, I didn't know what I needed, and was overwhelmed with all the choices available to me. Eventually, I made the decision, and am quite happy with the phone. But I was stuck until I decided to move forward.
I know that this is a small example, but that is the point. I share this experience to show how easy it is to fall into the trap. No imagine if a whole factory hinged on your decision? A company? Make a decision and move forward, before someone makes a decision for you (or changes the situation on you).