Article: Astrology
Section: Effectiveness

Question: What is the "Mars effect"?

Astrology has not demonstrated its effectiveness in controlled studies and has no scientific validity, and as such, is regarded as pseudoscience.
Where astrology has made falsifiable predictions, it has been falsified.
Shawn Carlson's double-blind chart matching test, in which twenty eight astrologers agreed to match over 100 natal charts to psychological profiles generated by the California Psychological Inventory (CPI) test, is one of the most renowned tests of astrology.
The experimental protocol used in Carlson's study was agreed to by a group of physicists and astrologers prior to the experiment.
Astrologers, nominated by the National Council for Geocosmic Research, acted as the astrological advisors, and helped to ensure, and agreed, that the test was fair.
They also chose twentysix of the twentyeight astrologers for the tests, the other two being interested astrologers who volunteered afterwards.
The astrologers, from Europe and the United States, helped to draw up the central proposition of natal astrology to be tested.
Published in "Nature" in 1985, the study found that predictions based on natal astrology were no better than chance, and that the testing "clearly refutes the astrological hypothesis".
In 1955, astrologer and psychologist Michel Gauquelin stated that although he had failed to find evidence to support such indicators as the zodiacal signs and planetary aspects in astrology, he had found positive correlations between the diurnal positions of some of the planets and success in some professions which astrology traditionally associates with those planets.
The best-known of Gauquelin's findings is based on the positions of Mars in the natal charts of successful athletes and became known as the "Mars effect".
A study conducted by seven French scientists attempted to replicate the claim, but found no statistical evidence.
They attributed the effect to selective bias on Gauquelin's part, accusing him of attempting to persuade them to add or delete names from their study.
Geoffrey Dean has suggested that the effect may be caused by self-reporting of birth dates by parents rather than any issue with the study by Gauquelin.
The suggestion is that a small subset of the parents may have had changed birth times to be consistent with better astrological charts for a related profession.
The sample group was taken from a time where belief in astrology was more common.
Gauquelin had failed to find the Mars effect in more recent populations, where a nurse or doctor recorded the birth information.
The number of births under astrologically undesirable conditions was also lower, indicating more evidence that parents choose dates and times to suit their beliefs.
Dean, a scientist and former astrologer, and psychologist Ivan Kelly conducted a large scale scientific test, involving more than one hundred cognitive, behavioural, physical and other variables, but found no support for astrology.
Furthermore, a meta-analysis was conducted pooling 40 studies consisting of 700 astrologers and over 1,000 birth charts.
Ten of the tests, which had a total of 300 participating, involved the astrologers picking the correct chart interpretation out of a number of others which were not the astrologically correct chart interpretation (usually 3 to 5 others).
When the date and other obvious clues were removed no significant results were found to suggest there was any preferred chart.