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Mars effect

The Mars effect is the name given to Michel Gauquelin's astrobiological claim that when Mars is in certain sectors of the sky great athletes are born in numbers indicative of a non-chance correlation. If this were true, astrologers believe that it would provide support for their theories that the things in the sky are actively influencing who and what we become. However, such correlations are notoriously slippery. They are ambiguous (who counts as a "great" athlete?), and significant correlations between variables that are not significantly related are expected to occur occasionally.

In any case, what Gauqelin claims about Mars and athletes isn't true, according to a study by several French scientists. They took a sample of over 1,000 French athletes and compared them to thousands of others for birth times, dates and location of Mars at birth. The study didn't support the Mars effect.

Gauquelin preferred to call his work in this area astrobiology rather than astrology. He also claimed to find a significant correlation between Jupiter and military prowess, as well as between Venus and artists.

See also astrology, clustering illusion, confirmation bias, Forer effect, law of really large numbers, occult statistics, post hoc fallacy, regressive fallacy, and  subjective validation.

further reading

books and articles

Benski, Claude, et al., The "Mars Effect" (Amherst, NY: Prometheus Books, 1996).

Dean, Geoffrey, Arthur Mather and Ivan W. Kelly, "Astrology,"   in The Encyclopedia of the Paranormal, ed. G. Stein (Amherst, N.Y.: Prometheus Books, 1996).

Ruscio, John. "The Perils of Post-Hockery," in the Skeptical Inquirer, November/December, 1998.


"Coincidences: Remarkable or Random?" by Bruce Martin

The Mars effect in retrospect by J. W. Nienhuys

A Brief Chronology of the "Mars Effect" Controversy by Kenneth Irving

The True Disbelievers (Read about the exciting history of this subject, complete with charges of disingenuous skepticism by Marcello Truzzi and Jim Lippard - a real potboiler!)

Last updated 19-Dec-2013

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