Well, now we know that spanking results in lower IQs for children than those that aren't spanked.  Of course, maybe once we figure out what IQ really means (if anything) this study might actually have some significance.

"But the 2- to 4-year-olds who were spanked scored 5 points lower on the
IQ test than those not spanked. For children ages 5 to 9, the spanked
ones scored on average 2.8 points lower than their unspanked
counterparts.

The results, he said, were statistically significant."

The question that needs to be asked is why these results should be considered statistically significant, when the variation itself isn't statistically significant enough to qualify as a repeatable score.

This is clearly an agenda driven study since the authors didn't bother to establish why they felt that spanking should be linked in some fashion to intelligence (nor to establish that IQ actually relates to intelligence).

This one should definitely get honorable mention in Josh Witten's Festival of Idiots.