What one of the psychiatrists I spoke to said what they really need to do is show the effects in a controlled study.
It is a randomized controlled study, meaning that similar patients were assigned at random to either get either Centrum or placebo.
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Given that the association between diet drinks and with vascular events is unexpected and unsupported by other research, a study that controlled for specific ingredients, such as the type of sweetener and caffeine content, is needed to assess whether there are grounds for a plausible mode of action.
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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.
Because the Framingham Heart Study is not a randomized controlled trial, it's still not clear if vitamin D is the real reason for the link (the vitamin's levels could drop in unhealthy people for other reasons), or if taking a supplement would lower the risk.
But a large, NIH-sponsored, carefully controlled study published in the Annals of Internal Medicine Monday reports that, unlike HRT, the supplement doesn't work to help hot flashes or other menopausal symptoms.
The ScanBrit randomised, controlled, single-blind study of a gluten- and casein-free dietary intervention for children with autism spectrum disorders.
Whatever the mechanism, though, this study provides what no previous study ever has: evidence from a controlled experiment that keystone species really exist.
For one, the groups noted the analysis is a retrospective study, not a prospective, randomized controlled clinical trial, which many regard as a gold standard for ferreting out safety concerns.
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Packer says this is the first placebo-controlled study in acute heart failure to show a clinical benefit.
All of the studies ran for at least a year, and all were randomized controlled trials, the most rigorous type of study.
The Cambridge group will begin a randomized controlled trial next month with 104 children involved, similar to the peanut study done already, but with controls, said researcher Dr. Andrew Clark of Cambridge University Hospitals.
To further study the reasons behind the findings, the researchers conducted a similar experiment in the controlled environment of a university lab.
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In a recent study (published in the journal Public Library of Science One) seven pairs of subjects controlled virtual avatars.
By contrast, the approach in modern medicine, one that has been validated in hundreds of thousands of controlled experiments, is to rigorously identify, and observe, any factors that may unfairly bias a study.
And in a study published last year, researchers in Australia showed in a double-blind, placebo-controlled trial that subjects with suspected gluten sensitivity had substantially fewer symptoms on a gluten-free diet than control subjects who unknowingly ingested gluten.
For the current study, Buijsse and his colleagues excluded anyone with a history of heart disease or stroke, and also controlled for age, diet, lifestyle, and other factors.
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