First , I used the equals sign not the less than sign . I was hoping to be more clear because most people jave no idea how to interpreted probabilities . Second , you ' re right . I should have been more clear and just gone all in with citations and a review of the statistical methods and data collection etc . I don ' t have the time . Here ' s a relevant passage presenting both sides of a metaanalysis . n commentary published along with the Gershoff study , George W . Holden , PhD , of the University of Texas at Austin , writes that Gershoff ' s findings reflect the growing body of evidence indicating that corporal punishment does no good and may even cause harm . Holden submits that the psychological community should not be advocating spanking as a discipline tool for parents . In a reply to Gershoff , researchers Diana Baumrind , PhD Univ . of CA at Berkeley , Robert E . Larzelere , PhD Nebraska Medical Center , and Philip Cowan , PhD Univ . of CA at Berkeley , write that because the original studies in Gershoff ' s metaanalysis included episodes of extreme and excessive physical punishment , her finding is not an evaluation of normative corporal punishment . Here ' s the link . The authors and publications are listed at the bottom . Compare for yourself .