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Topic.7 - Topic 7 Hypothesis tests based on a single sample...

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1 Topic 7 - Hypothesis tests based on a  single sample Sampling distribution of the sample mean  pages  187 - 189   Basics of hypothesis testing  pages  222 - 227   Hypothesis test for a population mean  pages  229 - 234   Hypothesis test for a population proportion  pages  283 - 284  
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2 Hypothesis testing We have already discussed how you can make decisions based on data  using confidence intervals. If someone claims a population parameter has a certain value, we only  believe the claim if the value is inside our confidence interval for the  parameter.  Hypothesis testing provides a more formal method for testing claims.
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3 Hypothesis testing hypothesis test  checks sample data against a claim or assumption  about the population. The claim being tested is called the  null hypothesis , H 0 . The null hypothesis typically represents the status quo or no change  belief. The  alternative hypothesis , H A , represents what we suspect is true. The researcher’s goal is typically to show that the alternative  hypothesis is true.
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4 Studying example A study reports that the mean time freshmen spend studying is 7.06  hours per week. A TAMU teacher feels that freshmen here spend more  time on average studying.   What are the appropriate null and alternative hypotheses?
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5 ImanAggie Redimix Remember the problem with the strength of the concrete and the  TxDot contract?  The company claims, based on information from  “Joe”, their Production Foreman, that the average is 3,200 psi, with a  standard deviation of 250? – Someone else at the company questions that that amount is  overstated, because if it’s lower than the claim, it opens the  company to potential lawsuits. – What are the null and alternate hypotheses in this case?
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6 Is the operation “status quo”? Our California-based company, produces rivets for use in the aircraft  industry.  Historically, these rivets have a mean diameter of .025  inches, with a standard deviation of .000001 inches (pretty tight  tolerance). A recent earthquake might have negatively impacted the average  width setting on our machines.   If they are now too wide, they won’t fit in the holes of the airplanes.   Conversely, if they’re too narrow, they “could” cause a safety issue. What are the null and alternate hypotheses in this case?
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7 TV Sitcom example The percentage of viewers that like sitcoms on average is about 35%  (that’s a madeup number, but assume that’s the base-line that the  execs allow to keep a show on the air).
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