Seriously, this is what is wrong with science today - it is driven by agenda instead of a search for knowledge and understanding. They started with an assumption: Children who get spanked have lower IQs. They then gathered data and pronounced:Children who get spanked have lower IQs because they were spanked, even when there is almost no evidence to support that conclusion. There is far more evidence that points toward socioeconomic and/or genetic factors. 
These "scientists" knew that any results would be horribly flawed because there are so many other factors that cannot be controlled a study like this, but they had an agenda and performed the study, and published the flawed results, anyway. They admit that the only way to get reliable results would be with a control group, which isn't going to happen for so many reasons, but they still went forward. If it wasn't so sad, it would be hysterically funny.
link...
These "scientists" knew that any results would be horribly flawed because there are so many other factors that cannot be controlled a study like this, but they had an agenda and performed the study, and published the flawed results, anyway. They admit that the only way to get reliable results would be with a control group, which isn't going to happen for so many reasons, but they still went forward. If it wasn't so sad, it would be hysterically funny.
link...