I figure that IF a slap needs to be administered, an open hand is sufficient, and only once at a time, for children under five. After that age, spanking tends to be counterproductive for most children (then again I don't have a hellion on my hands).
I can't believe all these sadists around here. My parents beat the snot out of me for every deed or misdeed. By my teens I was in full rebellion and hated both of them.
We never laid a hand on our kids. They are all grown, paired off well, and excellent people. My wife and I stopped alcoholism and child abuse in one generation and are darned proud of it. This "whack em, hit em, beat em" crap is so much hogwash.