"With regard to transcendental meditation’s claim of “508 scientific
studies”, only 24 (3%) of these were randomised controlled trials and
of these, at least 6 were published by lead-authors employed by
transcendental meditation- (TM)-linked institutions, primarily the
Maharishi University of Management. Such links naturally raise
questions about conflicts of interest and objectivity in the
reporting of results, particularly in the light of the strongly
commercialised nature of the TM technique.
Of the 24 studies of TM, 22 were clinical trials and 2 were
physiological trials assessing effects after brief training giving 37
comparisons. The author was the trainer in one study, while in 5
studies the author was employed by an institution that had formal
affiliations with the TM organisation. TM was compared to low
credibility controls in 19 comparisons, to moderate credibility
controls in 4 instances and to high credibility controls in 14
instances. Sample size ranged from 20 to 250 participants, sample
size per treatment arm ranged from 10 to 78. Drop-out rates varied
from 0% to 55%. In 13 studies the statistical methods were
inappropriate or not clearly described and in 16 studies the author’s
conclusions were not supported by the analysis and results. "
From http://www.researchingmeditation.org/