Unit 9-1

Unit 9-1 - Hypothesis Tests Hypothesis OneSampleMeans

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Hypothesis Tests Hypothesis Tests   One Sample Means
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Example 2:  A government agency has  received numerous complaints that a  particular restaurant has been selling  underweight hamburgers.  The restaurant  advertises that it’s patties are “a quarter  pound” (4 ounces). How can I tell if they really are  underweight? But how do I know if this x is one that I expect expect to happen or is it one that is unlikely unlikely to happen? Hypothesis test will help me decide!
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What are hypothesis tests? What are hypothesis tests? Calculations that tell us if a value occurs by  random chance  or not – if it is  statistically significant Is it . . . a random occurrence due to variation? a biased occurrence due to some other  reason?
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Nature of hypothesis tests - Nature of hypothesis tests - First begin by supposing the “effect” is  NOT  present Next, see if data provides evidence  against  the supposition Example: murder trial How does a murder trial work? First  - assume that the person is  innocent Then –  must must  have sufficient  evidence to prove guilty Hmmmmm … Hypothesis tests use the same  process!
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Steps: Steps: 1) Assumptions parameters 3) Calculations 4) Conclusion, in context Notice the steps are the same except  we add hypothesis statements –  which you will learn today
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Assumptions for z-test (t-test): Assumptions for z-test (t-test): Have an  SRS of context Distribution is (approximately)  normal Given Large sample size Graph data   σ  is known (unknown) YEA YEA These are the same assumptions as  confidence intervals!!
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Example 1:  Bottles of a popular cola are supposed  to contain 300 mL of cola.  There is some  variation from bottle to bottle.  An inspector, who  suspects that the bottler is under-filling, measures  the contents of six randomly selected bottles.  Are  the assumptions met? 299.4   297.7   298.9   300.2   297   301 Have an SRS of bottles Sampling distribution is approximately normal because the boxplot is symmetrical σ is unknown
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Writing Hypothesis statements: Writing Hypothesis statements: Null hypothesis  – is the statement being  tested; this is a statement of “no effect” or “no  difference” Alternative hypothesis  – is the statement  that we suspect is true H 0 : H a :
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The form: The form: Null hypothesis    H 0 : parameter = hypothesized value Alternative hypothesis    H a : parameter > hypothesized value    H a : parameter < hypothesized value    H a : parameter = hypothesized value
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Example 2:  A government agency has received  numerous complaints that a particular restaurant  has been selling underweight hamburgers.  The 
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This note was uploaded on 12/09/2011 for the course STATS 221 taught by Professor Nielson during the Fall '10 term at BYU.

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Unit 9-1 - Hypothesis Tests Hypothesis OneSampleMeans

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