What do you mean, “test” astrology?

That was the actual question someone asked me recently. I had said that whenever astrology is tested, it fails the test. Her reply was, what do you mean, “test” astrology? I said, well, compare the predictions made by astrology, to what actually transpires. (i.e., see if it works.) It seemed a pretty obvious reply. It seemed to confuse her, though.
Astrologers don’t like testing astrology to see if it works. Can’t say I blame them, because it doesn’t work. Think of this. An expert astrologer draws up your detailed chart based on your accurate natal data. You are given this horoscope, and two others of different people. Would you be able to tell which one is yours? Because if not, what does it mean to say that astrology works? Whenever this test is done, people are not able to do this with any greater probability than pure chance. (i.e. one in three would get it right.)
Possibly the most detailed test of astrology using this type of method, was performed by Shawn Carlson.  His paper, “A Double-blind Test of Astrology”, was published in the prestigious peer reviewed scientific journal Nature, in 1985. The interesting thing is that the San Francisco chapter of the National Council for Geometric Research recommended the 28 professional astrologers who took part, and (with Carlson), designed the tests. They also predicted, in advance, what they would consider to be a successful test.
Two tests were performed:
Test #1: Astrological charts were prepared for 83 subjects, based on natal data (date, time and place of birth), provided by the subjects. Each subject was given three charts: one chart based on their own natal data, and two charts derived from natal data of other people. Each subject was asked to identify the chart that most correctly described them. In only 28 of the 83 cases, the subject chose their own chart.  This is the exact success rate expected for random chance. The astrologers predicted that the subjects would select their own chart more that 50% of the time.
Test #2: 116 subjects completed California Personality Index surveys and provided natal data (date, time and place of birth). One set of natal data and the results of three personality surveys (one of which was for the same person as the natal data) were given to an astrologer who was to interpret the natal data and determine which of the three CPI results belonged to the same subject as the natal data. In only 40 of the 116 cases, the astrologers chose the correct CPI. As with test #1, this is the exact success rate expected for random chance. The astrologers predicted that they would select the correct CPI profiles in more that 50 per cent of the trials.
Conclusion by Carlson:
“We are now in a position to argue a surprisingly strong case against natal astrology as practiced by reputable astrologers. Great pains were taken to insure that the experiment was unbiased and to make sure that astrology was given every reasonable chance to succeed. It failed. Despite the fact that we worked with some of the best astrologers in the country, recommended by the advising astrologers for their expertise in astrology and in their ability to use the CPI, despite the fact that every reasonable suggestion made by advising astrologers was worked into the experiment, despite the fact that the astrologers approved the design and predicted 50% as the “minimum” effect they would expect to see, astrology failed to perform at a level better than chance.
“I have not yet received a serious scientific challenge to the paper. The newsletter of the American Federation of Astrologers Network published a response in January (1986). I was very disappointed to see that it largely consists of personal attacks. Its few substantive criticisms are attributable to ignorance of the experiment, of the CPI, and of basic scientific methodology.”
So the astrologers failed their own test. Does this mean they gave up astrology as being useless? Of course not: they are totally closed minded to the possibility that astrology doesn’t work. Of course, in science one test alone doesn’t decide things. That’s why I have summarized below an additional  similar types of tests that astrology failed.

  1. Compiled personality profiles from biographies of 2000 sports figures, actors, scientists, and writers.  Compared these profiles with personality traits associated with the sign of the sun, moon, and ascendant according to eight astrology texts.  No correlation was found using either the sidereal or tropical zodiac

2. Examined records of suicides in NYC from 1969 to 1973. Selected all suicides who were born in NYC and for which birth data was available. This resulted in 311 suicide cases.   For each of these, a control subject was randomly chosen who was born in the same borough and year.  The suicides and matching controls were divided into three groups according to year of suicide.  A computer program was used to test 100,000 different astrological factors in each of the 622 birth charts for significance between suicide and control groups.  None of the factors consistently correlated with the suicide cases. Examined records of suicides in NYC from 1969 to 1973. Selected all suicides who were born in NYC and for which birth data was available. This resulted in 311 suicide cases.
3. All found no correlation between sun sign and personality traits as measured by standardized psychological tests, mostly the California Personality Inventory (CPI). However, Pellegrini found a slight correlation between the CPI femininity index and season of birth.
4. Compiled natal charts and results of Minnesota Multiphasic Personality Inventory and the Leary Interpersonal Check List for 196 subjects. Compared 13 personality traits with sun signs, signs and houses of the moon and 8 planets, and with five planetary aspects.  No correlations were found. These two studies found no correlation between sun sign and personality traits measured by the CPI, including the femininity index.
5. Studies found correlations between astrological factors and the Introversion/Extroversion index of the Eysenck Personality Inventory. Showed that the correlation above could be explained by the fact that some of the subjects knew what the expected results would be for their astrological.
6. Studies found no correlation between astrological factors (sun and planetary) and personality, including the introversion/extroversion index.
7. A double blind test of astrologer John McCall was organized at the University of Virginia by Charles Tolvert and Philip Ianna.  McCall claimed an 80 percent success rate in choosing the correct natal horoscope for a subject from three false ones.  Twenty-eight subjects were chosen according to McCalls requirements (naturally born Caucasians).  McCall had 7 successes out of 28 trials, exactly the number predicted by chance.
8. The studies found no correlation between marriage/divorce rate and sun sign combinations in the state of Michigan and the city of Amsterdam respectively. John Mc Gervey Physicist Western Reserve University Found that the sun signs of 6,000 politicians and 10,000 scientists were randomly
9. Astrological readings were done for a groups of subjects.  The content of some of the readings were reversed (changed phrases describing the subject to their opposites). Subjects reported that both the reversed and normal readings applied 95 per cent of the time
10. Found no correlation between occupation and the zodiac signs containing Mercury, Venus, Mars, Jupiter, Saturn, and the Moon at the time of birth.
11. Found random distribution of the house containing Saturn for successful individuals, and the house containing Mars for murderers.
12. Found no correlation between occupation, medical problems, height, longevity, and the zodiac signs containing Mercury, Venus, Mars, and Jupiter at the time of birth.
13. Pretty much the same study and results as the previous reference. Additionally, no correlation was found between occupation, medical problems, etc. and angular separation (along the ecliptic) of planet pairs at time of birth.
14. Astrologers prepared horoscopes for subjects correct natal data. Reversed charts were then constructed from the correct charts by retaining the sun sign, but reversing all of the planetary aspects. Half of the subjects were given correct charts, the other half were given reversed charts.  There was no correlation between the perceived accuracy of the charts and whether the subject was given a correct or reversed chart.
15. Horoscopes were prepared for correct natal data and for a birth date 5 years and 6 months before the correct date, with the correct sun sign retained.  Thirty subjects were given the correct and incorrect charts.  Half of the subjects picked the correct chart, half chose the incorrect chart.
16. Six expert astrologers independently attempted to match 23 astrological birth charts to the corresponding case files of 4 male and 19 female volunteers. Case files contained information on the volunteers’ life histories, full-face and profile photographs, and test profiles from the Strong-Campbell Vocational Interest Blank and the Cattell 16-P.F. Personality Inventory. Astrologers did no better than chance or than a non-astrologer control subject at matching the birth charts to the personal data; this result was independent of astrologers’ confidence ratings for their predicted matches. Astrologers also failed to agree with one another’s predictions.
17. A study of 2,000 people, most born within minutes of one another, tracked over several decades. The study looked at more than 100 different characteristics, ranging from IQ to ability in art and sport, from anxiety levels to sociability and occupation – all of which astrologers claim are influenced by heavenly bodies. He found no evidence of the similarities that astrologers would have predicted.
18. The experimenters found no evidence of similarities between the “time twins”. “The test conditions could hardly have been more conducive to success… but the results are uniformly negative,” the research report said.
19. Dean said that the consistency of the findings weighed heavily against astrology: “It has no acceptable mechanism, its principles are invalid and it has failed hundreds of tests. But no hint of these problems will be found in astrology books which, in effect, are exercises in deception,” he said.
20. Dean is ready for a torrent of criticism: “I’m probably the most hated person in astrology because I’m regarded as a turncoat.”  The research undermined the claims of astrologers, who typically work with birth data far less precise than that used in the study.  Dean said: “They sometimes argue that times of birth just a minute apart can make all the difference by altering what they call the ‘house cusps’,” he said. “But in their work, they are happy to take whatever time they can get from a client.”
21. In 1971 the Survey Research Centre of the University of California Berkeley sampled 1000 adults in the bay area getting information on natal signs and lots of attributes claimed by astrology to correspond. For instance, Leos are supposed to have good leadership qualities. An analysis by Ralph Bastedo found no correlation for leadership, political stand, intelligence, belief in astrology, musical ability, artistic ability, confidence, creativity, occupation, religion, ability to make friends, to organize or to feel deeply. This showed that these tendencies do not differ between signs, so natal signs cannot be used to predict personality traits.
22. In 1979 Michel Gauquelin put an advertisement in Ici-Paris offering a free horoscope. Recipients were asked to reply saying how accurate they and their friends found the horoscope. Of the first 150 replies, 94% percent said it was accurate as did 90% of their friends and family. Unfortunately, they all got the same horoscope, that of Dr. Petiot, a notorious mass murderer.
23. In 1985, Harry Edwards checked all the predictions from Old Moore’s Almanack for 1984. These were written by a couple of top astrologers. Of the 200 predictions it was possible to check, less than 5% materialized and practically all of those could have been based solely on probability, prior knowledge or astute speculation. Astrologers are no better than pastry cooks, taxi drivers or any of us at predicting.
24. On June 7, 1989 on American television, James Randi offered $100,000 to any psychic or Astrologer who could prove the truth of their claims. An astrologer who took up the challenge was given the birth information of twelve people and had cast their charts. He interviewed the twelve without knowing who was who and was to identify them by matching them with horoscopes. He got none right. (Note: Randi now offers a $1 Million prize.)
25. Finally, Michel Gauquelin created a long running affair, starting in the late 60s, called the Mars effect with some research that looked very promising for astrology. He collected enormous amounts of data from catalogues of famous people ending up with data for thousands of sporting champions, scientists, actors and writers. He found statistically significant correlations between the birth of sports champions and the position of Mars, between actors and Jupiter, between scientists and Saturn and between journalists and Moon. This shouldn’t have been too much encouragement because it was only four planets, only four professions, and only for the top couple of percent of those professions. He found no correlations at all for any planet with random samples.
Because of the enormous amount of data it was difficult to reproduce and one attempt at refuting it boiled into a scandal where doubt was cast on the credibility of the refuters. Eventually, a French group, with Gauquelin’s cooperation, set up another test of over a thousand sports champions and found a negative result. Gauquelin then argued that some of the champions weren’t champions at all and that several other champions had been missed and should have been included. Needless to say these changes produced a positive result but are clearly post-hoc data manipulation introducing bias.
Since none of these tests are positive for a random sample of people it depended exclusively on how you define champion. Gauquelin wasn’t cheating or insincere but he was giving himself permission to select his data by focusing on champions and it was just too much work to find nothing.