Statistical Sciences 1024A/B Chapter Notes - Chapter 12: Sample Space, Randomness, Random Variable
20 Apr 2017
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Chance behaviour is unpredictable in the short run but has a regular and predictable pattern in the long run. This is why we can use probability to gain useful results from random samples and randomized comparative experiments. Random: individual outcomes are uncertain but there is a regular distribution of outcomes in a large number of repetitions. Relative frequency (proportion of occurrences) of an outcome settles down to one value over the long run. That one value is then defined to be the probability of that outcome. Relative frequency probabilities: can be determines (or checked) by observing a long series of independent trials (empirical data, experience with many samples, simulation (computers, random number tables. That is, an event is a subset of the sample space: a probability model is a mathematical description of a random phenomenon consisting of 2 parts: a sample space s and a way of assigning probabilities to events.
