Posted on

# base rate fallacy psychology example

5 6 7. What is the chance that Sara is innocent? Base rate neglect is a term used in cognitive psychology and the decision sciences to explain how human reasoners, in making inferences about probability, often tend to ignore the background frequencies. An individual object or person has a high representativeness for a category if that object or person is very similar to a prototype of that category. This problem has been solved! Although it seems to make sense, it is actually bad reasoning. The problem should have been solved as follows: - There is a 12% chance (15% x 80%) the witness correctly identified a blue car. The neglect or underweighting of base-rate probabilities has been demonstrated in a wide range of situations in both experimental and applied settings (Barbey & Sloman, 2007). Why are spam filters claimed to be so accurate and yet mess up so often? In the above example, where P(A|B) means the probability of A given B, the base rate fallacy is the incorrect assumption that: However, the correct expression uses Bayes' theorem to take into account the probabilities of both A and B, and is written as: Thus, in the example the probability is overestimated by more than 100 times, due to the failure to take into account the fact that there are about 10000 times more nonterrorists than terrorists (a.k.a. In making rough probability judgments, people commonly depend upon one of several simplified rules of thumb that greatly ease the burden of decision. Before leaving the topic of base-rate neglect, we want to offer one further example illustrating the way in which the phenomenon might well have serious practical consequences. Description: Ignoring statistical information in favor of using irrelevant information, that one incorrectly believes to be relevant, to make a judgment. In a city of 1 million inhabitants there are 100 known terrorists and 999,900 non-terrorists. On the psychology of prediction. (1973). This classic example of the base rate fallacy is presented in Bar-Hillel’s foundational paper on the topic. A cheating detection system catches cheaters with a 5% false positive rate. The Base Rate Fallacy. A generic information about how frequently an event occurs naturally. IMPORTANT:This page has used Creative Commons Licensed content from Wikipedia in either a refactored, modified, abridged, expanded, built on or 'straight from' text content! The above rates are not to far off actual figures as of 2015 the population for the age group of 10-24 years was estimated at 52,275 in the Townsville region (ABS, 2017). Popular induction: Information is not always informative. The base rate fallacy is a tendency to focus on specific information over general probabilities. The gambler’s fallacy is an intuition that was discussed by Laplace and refers to playing the roulette wheel. [2][3][4], In some experiments, students were asked to estimate the grade point averages (GPAs) of hypothetical students. I also tell you that green … [attribution needed], Psychologists Daniel Kahneman and Amos Tversky attempted to explain this finding in terms of a simple rule or "heuristic" called representativeness. In J.S. In this chapter we will outline some of the ways that the base-rate fallacy has been investigated, discuss a debate about the extent of base-rate use, and, focusing on one Base rate fallacy definition: the tendency , when making judgments of the probability with which an event will occur ,... | Meaning, pronunciation, translations and examples Learn vocabulary, terms, and more with flashcards, games, and other study tools. The base rate fallacy is a tendency to focus on specific information over general probabilities. Imagine a Townsville Policeman has developed a youth criminal detector that we shall call the YCD. Sign In Sign Up. The base rate probability of one random inhabitant of the city being a terrorist is thus 0.0001 and the base rate probability of a random inhabitant being a non-terrorist is 0.9999. if the camera sees a non-terrorist, it will not ring the bell 99% of the time, but it will mistakenly ring it 1% of the time (the false-positive rate is 1%). Top Answer. Enter any psychology term. The base rate fallacy is committed when a person focuses on specific information and ignores generic information relating to the overall likelihood of a given event. When it checks a coin, it only gets it wrong 1% of the time. The base rate fallacy is related to base rate, so let’s first clear about base rate. The YCD is so advanced that just by taking a saliva sample it can tell if youths aged 10-24 years old are either a criminal or not. In other words, the intuition is that after a series of n equal outcomes, the opposite outcome will occur. For example, the base rate of suicide in the general population is less than 1%, whereas the base rate of suicide for a more restricted population, for example, among patients with borderline personality disorder, may be as high as 10%. The 'number of non-terrorists per 100 bells' and the 'number of non-bells per 100 terrorists' are unrelated quantities, and there is no reason one should equal the other. Question: What Is A Good Example Of Base Rate Fallacy ? The software has two failure rates of 1%: So, the failure rate of the camera is always 1%.