Even if spanking results in (slightly) more aggressive children, the study misses the point. Spanking is a response to the immediate problem of disobedient and/or destructive children. For example, let’s say your child wants to play with matches. You tell them, “No!” and use non-violent parenting techniques, but you find the child secretly playing with a book of matches. What are you going to do? In this particular case, the disobedience might end up in the child’s death. Are you going to refuse to spank the child, because it MIGHT result in SLIGHTLY more aggressive behavior from the child later on? If so, you’re a poor excuse for a parent. Bottom line, this study went searching for harmful effects of spanking, and no surprise, it found some.
BTW, I very, very rarely used spanking on my children, but sometimes nothing less seemed appropriate to the situation.