Is it a good or bad idea to give this supplement to kids whose sleep schedules may be thrown off by a time change or some other factor?

CNN: Should your teen take melatonin for help with sleep?

Researchers don't yet know how to explain these correlations -- and since the study was not a controlled trial, it's not clear whether marijuana or some other factor in marijuana users' lifestyles actually accounted for the beneficial effects.

CNN: Marijuana: The next diabetes drug?

Yet, it is difficult to be certain that this is because they lack coverage or whether some other factor is at work.

FORBES: Can Markets Work in Medicine?

Singer notes a number of possible explanations for why the other two groups might not have seen the behaviors initially reported, including compensation thanks to other genes, some unknown environmental factor, or variability in the knocked-out gene.

FORBES: Mouse Behavior From Autism Studies Not Reproducible