A recent article in Yahoo! news network describes research on spanking and mental health. The journalist reports:
Corporal punishment was associated with increased odds of anxiety and mood disorders, including major depression, panic disorder, post-traumatic stress disorder, agoraphobia and social phobia. Several personality disorders and alcohol and drug abuse were also linked to physical punishment, the researchers found.
The study, originally published in the journal Pediatrics, intended to test the effects of physical punishment separately from more severe physical or sexual abuse. The journalist reported that the method involved
about 34,000 individuals aged 20 or older gathered from the U.S. National Epidemiologic Survey on Alcohol and Related Conditions. Participants were questioned face-to-face and asked, on a scale of "never" to "very often," how often they were ever pushed, grabbed, shoved, slapped or hit by their parents or another adult living [in] their home.
a. The journalist's story mentions that while the study shows that physical punishment is associated with some mental illnesses, the results cannot "prove that one causes the other." Why not? What are three possible causal paths for this association? (Hint: Think about both temporal precedence and the third variable problem)
Part of the story reports that
The researchers adjusted the data to take into account socio-demographic factors and any family history of dysfunction.
b. Was family history of dysfunction one of your third variables in question a? If so, what does the above statement mean?
One of the experts who was interviewed about this study said,
"While it's a well-done study, looking at a national data sample, there are limitations in the way the study was done," said Dr. Andrew Adesman, chief of developmental and behavioral pediatrics at Steven and Alexandra Cohen Children's Medical Center in New Hyde Park, N.Y. "There are limitations to relying on adults recalling childhood experiences...."
c. This expert is evaluating two of the big validities. Which of his quoted statements evaluate which validities, and why?
a. The two variables in this association are a history of physical punishment and a diagnosis of mental illness. It could be the case that physical punishment causes mental illness. It could also be the case that kids who show early signs of mental illness (somehow) cause their parents to be more physical with them. Or, it is possible that a third variable, such as family dysfunction or poverty, is associated with both mental illness and physical punishment.
b. The statement means that the researchers used a multivariate correlational design, testing whether there is still a link between spanking and mental illness even when controlling for family dysfunction. Since the link is still there, it means that family dysfunction can actually be ruled out as a third variable explaining the relationship.
c. The expert praised the external validity of the study when he said, "While it's a well-done study, looking at a national data sample". But he criticized the construct validity of the study when he said, "there are limitations to relying on adults recalling childhood experiences". By mentioning that people may not accurately recall their childhoods, this expert is suggesting that the study's operationalization of spanking may have been flawed.