1、Chapter 10Inferences on Two Samples10.1Inference about Means:Dependent SamplingA sampling method is independent when the individuals selected for one sample does not dictate which individuals are to be in a second sample.A sampling method is dependent when the individuals selected to be in one sampl
2、e are used to determine the individuals to be in the second sample.Dependent samples are often referred to as matched pairs samples.EXAMPLEIndependent versus Dependent SamplingFor each of the following,determine whether the sampling method is independent or dependent.(a)A researcher wants to know wh
3、ether the price of a one night stay at a Holiday Inn Express Hotel is less than the price of a one night stay at a Red Roof Inn Hotel.She randomly selects 8 towns where the location of the hotels is close to each other and determines the price of a one night stay.(b)A researcher wants to know whethe
4、r the newly issued“state”quarters have a mean weight that is different from“traditional”quarters.He randomly selects 18“state”quarters and 16“traditional”quarters.Their weights are compared.In order to test the hypotheses regarding the mean difference,we need certain requirements to be satisfied.A s
5、imple random sample is obtained the sample data is matched pairs the differences are normally distributed or the sample size,n,is large(n 30).Step 4:Compare the critical value with the test statistic:Step 5:State the conclusion.EXAMPLE Testing a Claim Regarding Matched Pairs DataSource:ExpediaTest H
6、ypothesis Is the differences distribution normally distributed?Step 1.Structure the Hypothesis H0:u=0 H1:u 0 Step 2 give=0.05 Critical values t=2.26216 C=(2.26216,infinity)Step 3 Test Statistic d=31,s=9.11 21.103/11.931/0nsdtd Step 4.t is in the critical region.Step 5.Conclusion:No evidence support
7、H0EXAMPLE Constructing a Confidence Interval for the Mean DifferenceConstruct a 90%confidence interval for the mean difference in price of Hampton Inn versus La Quinta hotel rooms.Source:ExpediaChapter 10Inferences on Two Samples10.2Inference about Two Means:Independent SamplingStep 4:Compare the cr
8、itical value with the test statistic:Step 5:State the conclusion.EXAMPLE Comparing Two Means:Independent SamplingA researcher wanted to know whether“state”quarters had a weight that is more than“traditional”quarters.He randomly selected 18“state”quarters and 16“traditional”quarters,weighed each of t
9、hem and obtained the following data.The degrees of freedom used to determine the critical value(s)presented in the last example are conservative.Results that are more accurate can be obtained by using the following degrees of freedom:Lower Bound=Upper Bound=221212/212()ssxxtnn221212/212()ssxxtnnEXAMPLE Constructing a Confidence Interval about the Difference of Two MeansConstruct a 95%confidence interval about the difference between the weight of“state”quarters and“traditional”quarters.谢谢你的阅读v知识就是财富v丰富你的人生
