Because the cognitive and behavioral analyses were not specified before the study, however, those findings are considered preliminary until confirmed in more rigorous trials. (scientificamerican.com)
Then, in the 1990s, the results of rigorous trials of some of the most popular supplements, including beta carotene, vitamin E and vitamin C, started to come in. (newscientist.com)
But most women are never told that ultrasound has never been subjected to any such rigorous trials. (drmomma.org)