Class Meeting 17

# Class Meeting 17 - CHEN 3010 Applied Data Analysis Class...

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1 CHEN 3010 Applied Data Analysis Class Meeting #17 Tuesday, Oct. 26 th Today's Topics Reading for Thursday: pages 218-229 Homework #8 due next Thursday Nov 4 th , posted Reminder: Midterm #2 on Tuesday, Nov. 9 th 2-way Comparison Tests Inferences on Means Variances Known Unknown Equal Unequal

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2 Scenario: 2 samples are collected Are the means of the populations that the samples represent different or the same? Example Problem: Natural gas is sampled from two wells in a large field and the following methane analyses are made: 1 2 64 69 65 69 75 61.5 67 67.5 64.5 64 74 75 Well Methane Content (mole %) Questions that need to be addressed: Is the variance of each sample known? Or does it have to be estimated from the data? Are the variances of the two samples equal? What is the risk level for the test to determine whether the means are different?
3 Is the variance of each sample known? Or does it have to be estimated from the data? The latter is more likely here, but let's say that, because of a long history of measuring methane in natural gas, we know that the standard deviation of the measurement is 2%. 2 24 σσ = = [We'll handle the other cases later.] We're also saying here that the variances are equal.

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4 Hypothesis Test Case: variances known & equal 0 12 2 H: µµ = > or 0 2 0 0 −= −> Note: it is also possible to hypothesize a non-zero mean difference. 0 0
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## This note was uploaded on 10/11/2011 for the course CHEN 3010 taught by Professor Kompala,dh during the Spring '08 term at Colorado.

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Class Meeting 17 - CHEN 3010 Applied Data Analysis Class...

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