Biology 2244A/B Lecture Notes - Lecture 5: Sample Space, Conditional Probability, Frequentist Probability
12 Dec 2017
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Probability: percentage of times an event would occur in a long series of repetitions/trials. Frequentist approach: chance behavior is unpredictable in the short run, but has a regular predictable pattern in the long run. Proportion in a small amount of trials can be far from probability. Probability is empirical: based on observation (vs. theoretical) Classical approach: make an assumption about theoretical probabilities. Random phenomenon: event whose outcome we can"t know in advance with complete certainty, bus has a regular pattern of occurrences over many repetitions. Probability of event= # of ways that event can occur/total # of possible outcomes a. k. a. Ex. a die: one way to get a 4, 6 possibilities, so probability=1/6. Probability model: shows all possible outcomes of a random phenomenon and the probability of each outcome occurring. Sample space (s): set of all possible outcomes (ex. male, female baby) Event: outcome or set of outcomes of a random phenomenon (subset of sample space)
