Garrett took part in "clairvoyance" tests. One of the tests was organised by Joseph Rhine at Duke University in 1933 which involved cards with certain symbols that were placed in a sealed envelope and participants were asked to guess their contents. Garrett scored 2,433 correct hits in 10,900 cards. She performed poorly and later criticised the tests by claiming that the cards lacked a psychic energy called "energy stimulus" and that she could not perform clairvoyance to order.J. B. Rhine's ESP experiments involved the use of card decks with 5 symbols, so the probability of a correct guess was 1 in 5 or 0.2. That means with 10,900 cards guessed the chance expected number of correct guesses was 2,180. The exact cumulative binomial probability of Garrett's 2,433 hits out of 10,900 guesses in a standard ESP card test is associated with a probability of p = 0.000000001, which in turn is associated with a z score of 5.97. This is close to the estimate
z = (hits - N/5)/sqrt(Npq), where N = number of guesses, p = 0.2 and q = 1-p, or
z = (2433 - (10900/5))/sqrt(10900 * .2 * .8) = 6.06.
While Garrett might have been disappointed with her results, someone should have explained to her that from a statistical perspective her performance was astoundingly good and did support the idea of providing "clairvoyance to order."
Wikipedia's entry on Rhine and his ESP card test results is equally flawed. For details read the book, ESP After Sixty Years, on Google books. It shows that Rhine and his colleagues were well aware of all of the criticisms of their methods (sensory leakage, selective reporting, recording errors, etc.), they responded to those critiques by steadily improving and testing the new methods, and they showed that the ESP interpretation remained valid. That book also shows that dozens of other investigators had tried to replicate Rhine's work and that cumulatively they were successful. This book is also the forerunner of modern meta-analysis.
Update 1: When the Wikipedia entry on Garrett was edited by referring to this blog post, the correction was removed in 6 hours, citing my post as an "unreliable source." This would be funny if it wasn't so silly. I am simply pointing out a mathematical fact. I guess facts are not allowed on Wikipedia.
Update 2: There is a discussion on Wikipedia where editors assert that parapsychology is a pseudoscience, and this is why it doesn't deserve a balanced article. I guess some simply cannot accept that parapsychology is an elected affiliate in good standing with the American Association for the Advancement of Science, as I describe here on my evidence page. The AAAS is the world's largest scientific organization and as such it represents the scientific mainstream. To be an affiliate of the AAAS an organization must be approved by the AAAS Council and it must be consistent with the objectives of the AAAS: "To further the work of scientists, to facilitate cooperation among them, to foster scientific freedom and responsibility, to improve the effectiveness of science in the promotion of human welfare, and to increase public understanding and appreciation of the importance and promise of the methods of science in human progress." The Parapsychological Association, which I've been President of four times, is strongly in favor of these objectives. We are especially in favor of promoting scientific freedom to seriously investigate any topic without prejudice. That aspiration is apparently prohibited on Wikipedia.
The AAAS does not tolerate pseudoscience, nor does it include any so-called "skeptical organizations" in its list of affiliates. Wikipedia editors are ignoring the fact that parapsychology is sanctioned as legitimate by mainstream science. This is yet another fact disallowed on Wikipedia.
If Wikipedia was really interested interested in being a neutral, fact-based encyclopedia, it would disallow editorial prejudice from distorting articles on controversial topics, and it would end the ridiculous policy of allowing anyone, regardless of expertise, to edit articles anonymously. I urge readers of my blog to regularly view the Wikipediocracy site, which is doing a good job in exposing major problems with Wikipedia across all disciplines.
Update 3: The above-mentioned discussion on Wikipedia has been archived. A saved version of the same discussion is also available here. See the comments on this post from Ben for more details.