#1 - Why go outside? Why go to the possible danger? Someone outside can hide and wait......with his buddies. Someone outside is only going to steal or vandalize. Stuff can be replaced.
#2 - While outside who is protecting the family inside? While you are in the backyard who is kicking in the front door.
#3 - Inside your house you can move from room to room, in the dark, and observe what is going on outside without exposing yourself......er, position. Then if you see something you can decide what to do, scare off the neighbors tom cat or call 911.
#4 - If the noise is created by someone intent on doing you harm and they try to enter, you have the advantage. Baracade yourself and the family with the shotgun.
Side note....I hunt deer and elk by hiding in trees or behind cover in the shadows. I wait on the animal to move into my view so that I kill it.
My 2 cents
This is the correct answer.
You're much more likely to find trouble if you go looking for it. I always ask people who do stuff like this if the gun changes your plan any (i.e. would you still go outside if you didn't have the gun?). If the answer is that the gun changes your actions (in this situation), then you need to re-examine your mindset. The gun is not an extension of your ego, but a tool to protect yourself (and your family) from life-threatening situations. It is also not a badge.
9MM is the "tool" I will use to get to a "Real Gun" my AR-15 Colt 6920 with Eotech Scope.
Good to see that we've got enough new folks on the board for the caliber debate again - I swear that horse was twitching. Almost as cool as "Shotguns are the best home defense weapon" posted by folks who haven't ever patterned 00-buck at 10yards or less (as well as those who consider bird-shot good for home-defense).