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Section 4.2
Basic Concepts of Probability
Term | Definition |
---|---|
Descriptive Statistics | used to summarize or describe characteristics of data with tools such as frequency distributions, graphs, and measures of center and variation |
Inferential Statistics | used to make inference or generalizations about a population |
Rare Event Rule for Inferential Statistics | If, under a given assumption, the probability of a particular observed event is extremely small, we conclude that the assumption is probably not correct. |
Event | any collection of results or outcomes of a procedure |
Simple Event | an outcome or an event that cannot be further broken down into simpler components |
Sample Space | for a procedure consists of all possible simple events; that is, the sample space consists of all outcomes that cannot be broken down any further |
P | probability |
A, B, and C | denotes specific events |
P(A) | denotes the probability of event A occurring |
Rule 1: Relative Frequency Approximation of Probability | conduct (or observe) a procedure, & count the number of times event A actually occurs. Based on these actual results, P(A) is approximated as follows: P(A) = # of times A occurred divided # of times procedure was repeated |
Rule 2: Classical Approach to Probability | (requires equally likely outcomes) Assume that a given procedure has n different simple events & that each of those simple events has an equal chance of occurring. If event A can occur in s of these n ways, then |
Rule 3: Subjective Probabilities | P(A), the probability of event A, is estimated by using knowledge of the relevant circumstances |
Law of Large Numbers | as a procedure is repeated again and again, the relative frequency probability of an event tends to approach the actual probability |
Probability Limits | always express a probability as a fraction or decimal number between 0 & 1-impossible event is 0; certain to occur is 1. for any event A, the probability of A is between 0 & 1 inclusive. that is 0 < P(A) < 1 |
Complementary Events | the complement of event A, denoted by A, consists of all outcomes in which the event A does not occur. |