AG-Ch-7-Notes-WI10 - Chapter 7: Sampling Distributions How...

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1 Chapter 7 notes AG 1/28/2010 Chapter 7: Sampling Distributions How likely is something to happen? What are the chances of getting a ticket if you are actually going over the speed limit? What are the chances the economy will rebound in the next few months? We start out with questions and then try to determine probabilities of something happening. Some probabilities are easy to figure out. If you want to know the probability of picking the Ace of Hearts in a deck of cards it is straight forward 1/52. This is classical probability where we know the total number of outcomes and each outcome has an equal chance of happening. Most of the probabilities in our life though aren’t as easy as that. We need to either ask for experts opinions’ ( subjective probability) or collect some data ( empirical or statistical probability). # Some issues to consider when trying to determine probabilities are: o The quality of the data How was it taken? Is it random? Is it based on underlying conditions that change the probability Lack of independence between two events Conditional probability o Are events mutually exclusive (disjoint) or not? o What rules do you need to determine the probability of two events happening? P(A or B) P(A and B) o Does the data distribute itself in some known ways? Probabilities can be determined by using known distributions Relative frequencies used when you collect data Normal distribution many things arrange themselves in this distribution Binomial when there are just two outcomes Sampling Distributions - proportions Statistic and Parameter # A statistic is a numerical summary of sample data such as a sample proportion or sample mean # A parameter is a numerical summary of a population such as a population proportion or population mean. o In practice, we seldom know the values of parameters. o Parameters are estimated using sample data. We use statistics to estimate parameters.
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2 Chapter 7 notes AG 1/28/2010 Sampling Distributions # The sampling distribution of the sample proportion shows all possible values and the probabilities for those values. # The
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This note was uploaded on 05/18/2010 for the course MATH math 208 taught by Professor C.eckerle during the Winter '10 term at Delta MI.

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AG-Ch-7-Notes-WI10 - Chapter 7: Sampling Distributions How...

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