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BUS 308 Week 2 DQ 1 t-Tests
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A t-testiswhentheteststatisticfollows a t-distribution, andwanttostatisticallytestwhetherthenullhypothesisistrue. T-Testsareusedtotestifthedifferenceofmeansisstatisticallysignificant. Ittestsifthesampleisrepresentativeofthepopulations. Forexample, ifthemeanforvariable 1 is 20 andthemeanforvariable 2 is 28, wemaysaythemeansaredifferent. T-Testsmayshowthattheyarenotsignificantlydifferent, however, andwecan’tbaseourconclusiononthemeans’ differencesincethedifferenceinthesampleisnotrepresentativeforthepopulation. Paired t-Test, alsocalleddependent t test, areusedwhenthedataofvariable 1 anddataofvariable 2 werecollectedinparallelfromeachindividual, suchas “beforeversusafter” cases. Supposethemarketercollectedtheratingsdatabeforechangingtheproductpackagingandafterchangingit. Let’ssaytheAlphavalueis 0.05, whichindicatestheconfidencelevelis 95%, meaningweare 95% confidentaboutthestatisticaltestresults. Forthesestatistics, weonlyneedtolookintothe P-value, “P (T<=t) two-tail.” Ifitisbiggerthan 0.05, themeansarenotsignificantlydifferent. A Two-Sample t-Test, alsocalledanindependent t test, isusedtocomparethemeansoftwoindependentgroups. Tocomparethreeormorevariables, statisticiansuseananalysisofvariance (ANOVA). Ifthesamplesizeislarge, theyuse a z-test. 

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