An important question in any research is whether the expectation of the test person (placebo effect) or prejudice in the researcher could play a role in the effects measured in the Transcendental Meditation studies. Due to the large number of TM studies, people were able to compile comparative studies (meta-analyses), through which we are able to rule these factors out with a high degree of certainty
1. Studies of higher quality lead to better results
If the results were influenced by a certain prejudice of the researchers, and if they had tried to represent the results better than they were in reality, then later studies of higher quality (in which researchers have less chance to influence the result) should show a worse result. The contrary was true, as illustrated by these two examples:
The meta-analysis of 19 TM studies on tobacco, alcohol and drug addictions, with in total more than 4500 test persons, demonstrated that the 14 studies of the highest quality (“longitudonal” and “experimental”) had better results (effect values of .55 for alcohol; .97 for tobacco; and .91 for drugs) than the 5 studies of lower quality (“cross-sectional” and “restrospective”, effect values of .54, .79 and .64). Reference: Alcoholism Treatment Quarterly 11: 13–87, 1994
Another meta-analysis looked at all published randomised, controlled clinical studies on the effect of the Transcendental Meditation programme on blood pressure, comprising nine studies among 711 test persons. In the 3 studies with the highest research standards the effect was bigger (6.5 mm Hg decrease) than in the 6 studies of lower standard (4.5 mm Hg decrease). Reference: American Journal of Hypertension 21: 310–316, 2008.
2. Researchers with a neutral or negative attitude towards the TM organisation had better results than researchers linked to the TM organisation. This was demonstrated by a meta-analysis of 35 TM studies on anxiety. Researchers with a neutral or even negative attitude found an average effect of .89 compared to an effect of .72 to .77 for researchers who were affiliated with the TM organisation (for example researchers of the Maharishi University). There was no quality difference between published and unpublished studies. The average effect of all 35 studies was twice as big as the placebo effect (reference: Journal of Clinical Psychology 45: 957–974, 1989).
3. Those with low expectations about the TM technique prior to learning it, had the same results as those with high expectations. This rules out possible placebo effects (reference: Scientific Research on TM, Collected papers, Vol 1, 72, pp. 462-467).
4. The effect grew the longer the technique was practiced. In case of placebo effects or situations in which prejudiced researched could have influenced the results, the effect always decreases in the long-term, but the opposite occurred in TM studies (reference: Journal of Clinical Psychology 45: 957–974, 1989, Journal of Social Behavior and Personality 6: 189–248, 1991, Alcoholism Treatment Quarterly 11: 13–87, 1994).
5. Frequent TM practitioners have better results than irregular practitioners. This clearly demonstrates that the effect is in fact caused by TM.
In the addiction meta-analysis the effect among regular practitioners was 25% bigger than for irregular practitioners. Reference: Alcoholism Treatment Quarterly 11: 13–87, 1994.
In the 9-year long study on heart patients, in collaboration with the National Institute of Health, the effect even was 40% bigger. (43% fewer instances of heart attack, stroke, or death among all TM practitioners, 61% fewer instances among regular practitioners) reference: Circulation 120: S461 (Abstract), 2009.