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Unformatted text preview: Chapter 5 Probability Fall 2008 1 Chapter 5 Preview When we talk about probability , we are talking about a (mathematical) measure of how likely it is for some particular event to happen Probability deals with chance behavior We study outcomes , or results of experiments Each time we conduct an experiment, we may get a different result Probability models the longterm behavior of experiments Fall 2008 2 Chapter 5 Preview Descriptive statistics, describing and summarizing data, deals with data as it is Probability , modeling data, deals with data as it is predicted to be The combination of the two will let us do our inferential statistics techniques in future chapters Fall 2008 3 Probability Understanding Rules of Probability Probability relates shortterm results to long term results An example: A shortterm result: We can obtain 0, 1, 2, or 3 heads when flipping a coin 3 times A longterm result: A fair coin would yield heads 1/2 of the time we would like to use this theory in modeling Fall 2008 4 Probability Understanding Rules of Probability Relation between longterm and theory: The long term proportion of heads after a great many flips is 1/2 This is called the Law of Large Numbers as the number of repetitions of an experiment increases, the proportion with which a certain outcome is observed gets closer to the probability of that outcome Helpful Hint: Look over p. 224 of your textbook for more information about the Law of Large Numbers. Fall 2008 5 Probability Terms and Definitions Some definitions An experiment is a repeatable process where the results are uncertain Some definitions An experiment is a repeatable process where the results are uncertain An outcome is one specific possible result Some definitions An experiment is a repeatable process where the results are uncertain An outcome is one specific possible result The set of all possible outcomes is the sample space Some definitions An experiment is a repeatable process where the results are uncertain An outcome is one specific possible result The set of all possible outcomes is the sample space Example Experiment roll a fair 6 sided die One of the outcomes roll a 4 The sample space roll a 1 or 2 or 3 or 4 or 5 or 6 Fall 2008 6 Probability Terms and Definitions More definitions An event is a collection of possible outcomes we will use capital letters such as E for events Outcomes are also sometimes called simple events we will use lower case letters such as e for outcomes / simple events More definitions An event is a collection of possible outcomes we will use capital letters such as E for events Outcomes are also sometimes called simple events we will use lower case letters such as e for outcomes / simple events Example (continued) One of the events E = {roll an even number} Fall 2008 7 Probability...
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This note was uploaded on 02/14/2011 for the course STAT 250 taught by Professor Sims during the Spring '08 term at George Mason.
 Spring '08
 sims
 Probability

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