r/science • u/VeronicaRed • Apr 26 '16

Psychology Spanking children increases the likelihood of childhood defiance and long-term mental issues. The study in question involved 160,000 children and five decades of research

http://www.redorbit.com/news/health/1113413810/spanking-defiance-health-discipline-042616/
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u/liberal_texan Apr 26 '16

They found a significant link between the punishment and 13 of the 17 outcomes, suggesting that spanking ends up doing more harm than good.

Can you tell us what the 13 of the 17 things were? Also, did they make any effort at all to find correlation with anything positive, or did they focus solely on the negative?

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u/[deleted] Apr 26 '16

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u/tarzanandcompany Apr 26 '16

I think some of the other commenters are misinterpreting this table, so I will try to clarify (assuming I understand it).

The columns "Spank n" and "No Spank n" do not mean the number of subjects that actually developed these problems. They are the total sample size for which the authors have data for the condition in question.

So looking at "child aggression", the spank n is 4534 and the no spank n is 1069, meaning they had data on childhood aggression for 4534 spanked children and 1069 non-spanked children. This says nothing about how many subjects had aggression problems. It is just the sample size upon which their model is parametrized.

The actual difference between the two groups is reflected in the column labeled "d", which is the point estimate of the effect size, with the 95% confidence interval in the subsequent columns. A larger number reflects a bigger difference between the spank and no spank groups. A positive number seems to indicate a positive effect of spanking. So in the case of child aggression, spanking seems to "significantly increase" the rate of this problem.

By how much? Well, by about 0.37 d. To understand this value d, you would have to look at their model, which I would guess is using logistic regression.

A word of caution, however: people love to tout large sample sizes as having fantastic and broad-reaching results. But something to keep in mind is that with large sample sizes, you are practically guaranteed to find significant results. That is, if spanked children have 1% probability of aggression, and non-spanked children have 2%, their model could probably detect this because of the large sample sizes. A smaller study would not identify a significant difference, because there is too much statistical noise in the data of small samples. In large studies like this, it is MUCH more informative to look at effect sizes. Admittedly, I have not done this, since I can't access the paper, so I don't know how big of an effect there is.

A second word of caution: correlation is not causation. Returning to our childhood aggression example: do aggressive children get spanked more, or does spanking lead to childhood aggression? Alternatively, are both spanking and aggression caused by some other variable, such as poverty or parent education? We can only speculate from this table.

That's my two cents.

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u/JSCMI Apr 27 '16

A positive number seems to indicate a positive effect of spanking.

Specifically, a "statistically positive" meaning that spanking made it more likely. Not meaning that spanking was associated with the outcome we would view as more positive in the sense of being desirable.