lec6.1 - 139 Lecture 14: CHAPTER 6: HYPOTHESIS TESTING...

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139 Lecture 14: CHAPTER 6: HYPOTHESIS TESTING Example: Consider the population of weights (in kg) of all newborn babies in Canada for a particular year. In this case, the Population Mean is the average weight of all newborns in the population. An investigator may want to use a simple random sample of these weights to determine if there is sufficient evidence to answer questions like: Is > 3.2 kg? or Is < 3.2 kg? or Is 3.2 kg? Example: Consider the population of all lakes in Nova Scotia. A biologist may be interested in the following population proportion : = the proportion of all lakes in Nova Scotia that are seriously affected by acid rain. He/she may want to use a simple random sample of lakes from this population to determine if there is sufficient evidence to answer questions like: Is >.7? or, Is <.7? or, Is .7? When drawing conclusions about a population using information from a sample it is important to realize that one can NEVER be absolutely certain the conclusion is correct. This is because a sample, though it may be “representative” of the population, only contains part of all the information contained in the population.
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140 Large-Sample Tests for a Population Mean (Section 6.1, page 391) A statistical hypothesis , or just hypothesis , is a claim or assertion either about one or more population or process characteristics (parameters). Examples: 1) Parameter: = proportion of e-mail messages from hotmail that are undeliverable Hypothesis: 2) Parameters: 1 = true average lifetime for a particular name-brand tire (miles) 2 = true average lifetime for a less expensive store- brand tire Hypothesis: Example: A certain type of automobile engine emits a mean of 100 mg of oxides of nitrogen  x NO per second at 100 horsepower. A modification to the engine design has been proposed that may reduce x NO emissions. The new design will be put into production if it can be demonstrated that its mean emission rate is less than 100 mg/s. A sample of 50 modified engines are built and tested. The sample mean x NO emission is 92 mg/s, and the sample standard deviation is 21 mg/s. The question, therefore, is this: Is it plausible that this sample, with its mean of 92, could have come from a populations whose mean is 100 or more? This is the sort of question that hypothesis tests are designed to
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This note was uploaded on 06/20/2011 for the course STAT 2800 taught by Professor Paula during the Winter '11 term at UOIT.

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lec6.1 - 139 Lecture 14: CHAPTER 6: HYPOTHESIS TESTING...

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