Often times, we find ourselves with two viable options in a situation. We say that we have a 50/50 chance. If Option 1 fails, it means we should have gone with Option 2. This is very, very wrong.
One of my peeves is when people say that they have a 50/50 chance because there are two options. Statistics do not work that way. Your options do not affect the rate of success on your other options. If Option 1 is jumping out of an airplane with a green parachute and Option 2 is jumping out of an airplane with an identical orange parachute, you have a pretty high rate of success either way. If Option 1 is jumping out of an airplane with an anvil and Option 2 is jumping out of an airplane with a safe, you're pretty well screwed either way.
A similar issue comes with determining the results of a given action. I jump out of a tree. Either I die or I don't. 50/50. Wrong!
50/50 means that there is an equal likelihood between the two options. Jumping out of a 10-foot tree. The chance of death is not 50%; it is much lower. Jumping out of a 100-foot tree, the chance of death is well above 50%.
This is an issue I find more in speech than writing, but it still stands. Think about what you say. It doesn't always mean what you think it does. If you can take the time to plan and construct your words while writing, take the time to find out what your words really mean.