quite the opposite... especially with this breed... you MUST take your dog out... walk them around, introduce them to EVERYONE... SOCIALIZE! SOCIALIZE! SOCIALIZE!!! introduce them to the (friendly) neighborhood dogs while your pup is still too young to know he's supposed to be aggressive to other dogs... who knows, it may help... let everyone in the neighborhood meet and greet your dog, this serves several purposes... people see you don't have a killer, you have a DOG, they know what your dog LOOKS like so if it ever gets away/gets stolen/ etc they can identify the dog and let you know they saw it, and it gets your dog used to as many people as possible and makes them much more likely to never be aggressive to anyone... confine your dog to your back yard and they know no-one, and no-one knows your dog... it will create fearfullness and fear-aggression.
also, i'm no expert, but i would think that confining the dog to the backyard would make them more likely to jump the fence, because they wanna see what they are missing, if you at least take them out and about, they will satisfy thier curiosity... but then again, i'm no expert, so don't quote me on that one.