In 1960 a man by the name of Maharishi Yogi stated that if one percent of the population would meditate it would noticeably change the world for the better. Subsequently, meditating individuals affecting their environment is thus called the Maharishi Effect.
The first statistical evidence that the Maharishi Effect has some validity was done in 1987 and published in the Journal of Mind and Behavior. The group of participants in the study set out to influence the population of Manilla in the Philippines. The results of the study showed that indeed the crime rate in Manilla went down while the group was meditating in Manilla and then went back up after the group left. [Dillbeck, M.C., Cavanaugh, K.L., Glenn, T., Orme-Johnson, D.W., & Mittle-fehldt, V. (1987). Consciousness as a field: The Transcendental Meditation and TM-Sidhi program and changes in social indicators. The Journal of Mind and Behavior, 8, 67-104.]
Okay, so how do we know that this wasn't just a coincidence or a statistical error? We don't, except that there are other studies showing the same thing. The same type of study was conducted in Washington D.C. in 1993 by members from the Maharishi University of Management and was subject to an independent review process from members of other Universities and eventually published in 1999 in the peer reviewed journal Social Indicators Research. This study also found significant reduction in crime rates just like the Manilla experiment. [Social Indicators Research, 47, 153-201]