Probability theory began in the 16th century in attempts to analyze games of chance like dice, playing cards, and roulette wheels.. While much of the math we are taught has the ring of eternal certainty, in probability theory there remains some conflict. Bernard Beitman, M.D., is a visiting professor at the University of Virginia. The higher the probability of an event, the more certain we are that the event will occur. Then consider the window of time between the thought of your friend and the friend contacting you. What is the base rate for thinking of a friend? It is quite possible that different pieces of evidence that seem to point in the same direction do so coincidentally. 7 Rules of Friendship Can Improve Your Romantic Relationship. h�b```�D��B cb��� Carrying this banner, I valiantly strode forward into probability’s thicket of mathematical concepts and formulas and emerged to write a report. Used with permission of Dan Hunt, MD. Could Vigorous Physical Exercise Help People Live Longer? %PDF-1.5 %���� A Statistician’s Approach to Coincidences (Part 2), A Statistician’s Approach to Coincidences, Part 4. We also factor in the length of time since you last communicated with your friend. The probability of at least one such event occurring is 1 minus the probability that no such events occurred. And what about the importance of the contact to you and your friend? 0 Their improbability stimulates wonder—“what are the odds of this happening?” Probability theory, which is a branch of mathematics, promises to shed light on this defining aspect of meaningful coincidences. endstream endobj startxref Generally speaking, statistics is concerned with the past (the collected data) while probability is concerned with the future (the likelihood that something will happen). The Neuroscience of Feeling Surprised by Unpredictability, The Scarab: Jung Created a Coincidence within a Coincidence. If your friend communicates something of vital importance to you,  the coincidence becomes more improbable than if the friend just wanted to say “Hi”? Statistics is the study of the collection, analysis, interpretation, presentation, and organization of data. This circumstance arises from the possibility that, with certain rational ratios of the periods, the events may "lock in step". Then the probability of the coincidence is 0.005 x 0.01, or 0.0005 which is quite low, but certainly possible. Co-authored by Tara MacIsaac a reporter for the Epoch Times and editor for the Beyond Science section. She explores the new frontiers of science, delving into ideas that could help uncover the mysteries of our wondrous world. For example, “meeting someone who helps you to advance in work, career or education” will require different formulas than coincidences involving people who have numerous characteristics in common, like doppelgangers. Let’s arbitrarily estimate a low base rate for this thought at 0.005, or 5 out of 1000 thoughts about people. Also, different kinds of coincidences require different probability approaches. My confidence was bolstered by having gotten a Double A in a probability theory seminar at Swarthmore College. Personal meaning. 14 Traits Found in Highly Religious People, Research Suggests That Synchronicities Can Aid Psychotherapy, A New Personality Test Also Gauges Mental Health, Psychology Today © 2020 Sussex Publishers, LLC. We come to the best possible conclusion about (say) the probability of Given the importance of probability in defining coincidences, I combed some of the simpler math literature to come up with an approach. The content of this field is kept private and will not be shown publicly. We could similarly estimate the base rate of contact from that friend at 0.01, or 1 time out of 100 contacts. h��VmO�0�+��*��o�Ry)T&�n��C�^��&U&���s��@��1M�k�|�;�ϓ;m$aDE �&"0�b9�- U }H8לh����'\Y A����p�BH"�U0PDH�0+�"T �%�H� I�� GG�����,���.�t�. The purpose of probability theory is to understand randomness and uncertainty to enable us to more accurately predict the future. He is the former chair of the University of Missouri-Columbia department of psychiatry. %%EOF The two most prominent current methods  are the “frequentist” and Bayesian methods. Coincidences attract our attention because they seem weird, odd, or unlikely. What are the odds of these two events coinciding? Probability is the measure of the likeliness that an event will occur. For example, you think of a friend whom you have not thought about in years, and that friend contacts you shortly afterwards. In future posts I will explore how statisticians, psychologists and pragmaticians look at coincidence probabilities. calculation. A small time window (a few minutes or hours) makes the coincidence less probable than an interval of a few days or weeks. Would Moving to a New City or Country Make You Happier? Since then several sometimes conflicting methods of assessing probability have been developed. The frequentists rely on the familiar bell shaped curve while Bayesians insist that subjective estimates of probability play an important role in determining a final probability. rare-events. So this single thought about your friend, measured against all the thoughts about other people you’ve had over the years, has a pretty low base rate. 673 0 obj <>/Filter/FlateDecode/ID[]/Index[659 32]/Info 658 0 R/Length 74/Prev 347826/Root 660 0 R/Size 691/Type/XRef/W[1 2 1]>>stream Why are so many people drawn to conspiracy theories in times of crisis? The probability of this satisfactory coincidence is first evaluated, and it is found that the solution, while mathematically adequate, is of no value for practical application. 690 0 obj <>stream h�bbd``b`��@�� H�|�Y��x��6��$�����8A�k�2�� d12)�La`�����G� �E' 659 0 obj <> endobj Source: Thunder Bay, Canada. The probability is 1/2 (or a 50% chance) of either "heads" or "tails". Base rates. The calculation of the probability of this common coincidence becomes a daunting task. The base rate of a specific thought is the number of times that thought occurs divided by the total number of thoughts. Get the help you need from a therapist near you–a FREE service from Psychology Today. endstream endobj 660 0 obj <>/Metadata 98 0 R/Pages 657 0 R/StructTreeRoot 115 0 R/Type/Catalog>> endobj 661 0 obj <>/MediaBox[0 0 595.32 842.04]/Parent 657 0 R/Resources<>/Font<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI]>>/Rotate 0/StructParents 0/Tabs/S/Type/Page>> endobj 662 0 obj <>stream The probability of a coincidence is calculated by first looking at the base rate (frequency of occurrence) of each of the two independent events. I concluded that base rates, personal meaning and time windows contribute to the probability of a coincidence. Time windows. A week since the last contact would make the coincidence far more likely than several years since the last contact. Statistician’s Approach to Coincidences: What Are the Odds? A simple example is the toss of a coin. Even if we could solve this problem with complex equations involving time windows and personal meaning, a more fundamental problem precedes the development of the complex equations: how do we determine the actual base rates of each leg of the coincidence? �<5�X>M�w@���Ƥ�Y�Z�m60:��X����10HNLT���er�džI��%[��� �%*���b�t��3�搧���n��a��P�A�A��������A�A���)�Q������(��A�r�{CX�O���r���^LS�v0�31]gfaNbvaҙc���p�A��Ř�C���*�ـ�+�4#� �����e`�0 3I� PROBABILITY OF COINCIDENCE M A Muller MSc PhD University of Stellenbosch _____ SUMMARY Coincidences are more common than most people might expect. What is the base rate for contacts by friends from whom you have not heard for a “long” time? Probability usually, but not always, relies on data from statistics to make its predictions. It is quantified as a number between 0 and 1 (where 0 indicates impossibility and 1 indicates certainty). Since the events are independent, the probability that none occur is given by the product of the probabilities of each not occurring, ... coincidence. The probability of a coincidence is calculated by first looking at the base rate (frequency of occurrence) of each of the two independent events.