PSYC 241 Lecture 6: Lecture 6: Probability
Document Summary
In inferential stats, we never deal in certainty because of a sampling error. Probability is a method for measuring and quantifying the likelihood of obtaining a specific sample from a specific population. Defined (mathematically) as a fraction or a proportion. Probability of specific outcome determined by ratio comparing frequency of occurrence for that outcome to the total number of possible outcomes. P(event) = (# of ways an event can happen)/(# of possible events) P(heart) = (13 hearts in deck)/(52 cards in deck) = 0. 25. It is impossible to predict with perfect accuracy exactly which score(s) will be obtained when you take a sample from the population. Researchers rely on probability to determine the relative likelihood for specific samples. You cannot obtain exactly which value(s) will be obtained for a sample, but can determine which outcomes have high vs. low probability. When a population of scores is represented by a frequency distribution, probabilities can be defined by proportions of the distribution.
