Pre test check

| October 22, 2018

Pretest

Foreach ofthefollowing,statewhichtest ismostappropriatetothesituation.Be sureto specifytheexacttest.Forexample,apairedt-testwouldnot beappropriateinthesame circumstancesasanindependentt-test.Andkeepinmindthat“test”mayapplytoawide rangeofprocedures,including,forexample,confidenceintervalsorcorrelations.

1.Astudyisconductedtodetermineiftimeofdayhasanyeffectontestgrades.Anintroductory
psychologyclassisselectedforthestudy,becauseit hasastandardcurriculumtaughtacross manysections.Twoclassesare selectedfor eachtimeperiod:8:00AM,1:00PM,and5:30
PM.Outofthetotalpoolofaround40studentsforeachtimeperiod,15studentsareselectedat random,foratotalof45.Thetestisadministeredtoallstudents,andthetestresultsforthe studysubjectsareplacedinSPSS.Wewanttoknowifthereisastatisticaldifferencebetween thesetimeperiods.Whattestisappropriate?

(5pts)

2.Hicks lawpredictshowlong itwilltakea usertopickoutagivenelementonawebsitepage fromamongalltheotherelementsonthatpage.Becauseacertainwebsitewillbeusedmany thousandsoftimesperyearonanintranet,amajorcompanyengagesausabilityspecialistto testwhethertheHickspredictionholdsontwoproposedhomepagedesigns.Becausethe companyisreluctantto havetoomanyemployeesabsentfromworkstations,itspecifiesthat the testcaninvolveonlyfiveindividuals,andthatthereforethesamefivepeoplemusttestboth proposedinterfaces.Wewillwanttoknowif thereisasignificantdifferenceinthetimesfor eachinterface.Whatistheappropriatetest?

(5pts)

3.Laparoscopicsurgeryisa procedurefor threadingasmallflexibletubewithina patient’sbody toexploreorperformprocedures.Arecentstudywasconductedtoseewhatskillsamedical
studentnewtolaparoscopicsurgerymighthavethatwouldpredictshorterlearningtimes.One variablethatwasgatheredwastheamountoftimeastudenthadspentplayingvideogames beforestartinghislaparoscopictraining.Theresearcherwantstoseeifthetimespentgaming canpredictthetimeneededtoperfectlaparoscopicskills.Whatwouldbethecorrecttestto
apply?

(5pts)

4.Alargecompanyisconcernedaboutturnover,soitcommissionsasurveythatwillbegivento arandomgroupof1000employees.Thecompanythenwantstogetageneralideaofwhatthe resultswouldbeinthelargerpopulation,butwhileitwilllookatsignificanceindicators,itis notheavilyinterestedinsignificance,butinanestimateofcompany-wideresults.Whattest wouldbepropertorunhere?

(5pts)

Astudyisconductedintotimemissedfromwork,comparedwithoutsidetemperature.A
randomsampleof50employeesisextractedfromthehumanresourcesattendance
databaseandacorrelationisconducted.Thereisfoundtobeanrof.311atanalphaof.05, two-tailed.

5.Whatis thecriticalvalueofrforthepreviousparagraph?

(5pts)

6.Isther fromquestion5significant?

(5pts)

.jpg”>Refertothetablebelow.It givestwosetsoffigures,a predictedrainfallamountfroma radarimage,andanactualrainfallamountasmeasuredbyastandardraingauge.

(X)RadarRainPrediction

(Y)RainGauge

3.6

.0

2.0

1.2

1.1

1.2

1.3

1.3

1.8

1.4

2.1

1.4

3.2

2.0

2.7

2.1

2.5

2.5

3.5

2.9

3.9

4.0

3.5

4.9

6.5

6.2

7.3

6.6

6.4

7.8

7.Using the dataaboveandtheformulasnexttothetable,calculaterforthedatasetusingthe methodofleastsquares.(Youmay useanothersetofformulasifyoulike,buttheseare relativelysimple.)Showyourwork.Usethebackofthesheetsif
necessary.

(10pts)

.gif”>8.Interpretther
valueofproblem7.Bethorough.

.gif”>.gif”>(5pts)

.gif”>9.Statether2valueofproblem7andinterpret.Bethoroughinyourinterpretation

.gif”>.gif”>(5pts)

10.WhatistheYinterceptforthedatafromproblem7?

(5pts)

11.Whatistheconfidenceintervalof problem7forX=3.5withalphaof.05?

(10pts)

12.Whatisthepredictionintervalof problem7forX=3.5withalphaof.05?

(10pts)

Refertothefollowingchartsandtablesforthenextquestions.

Thisisacomparisonofaveragefemalelifeexpectancyaroundtheworld,comparedwith theinfantmortalityrates.

.gif”>.gif” alt=”Text box: infantmortality(deathsper1000livebirths)”>200.0

150.0

100.0

50.0

0.0

40 50

60 70 80

.gif”>.gif”>.gif”>Averagefemalelifeexpectancy

13.Whatisthenofthe samplesfrom theanalysisshownabove?

(5pts)

14.Is theassociation(correlation)inthedataabovepositiveornegative?

(5pts)

15.Writethecompleteregressionequationforthemodelabove.Donotincludetherandomerror
term.

(5pts)

.gif”>16.Isregressionorcorrelationanappropriatetestforthedatasetabove?Explain.

.gif”>.gif”>(10pts)

ExtraCredit(upto10pts)

Asurveywastakenaboutwhetherstudentsandstaffparkedinlots,orparkedingarages.The tasknowis toseeif the differencesaresignificant,andwhateverelsethedatacanreveal.

Calculatethechi-square,alongwiththecriticalvalueandsignificance,ofthefollowingdata. Showyourwork.Interprettheresultasthoroughlyasyoucan.

Instructors

Students

Totals

ParkedinLots

80

68

ParkedinGarages

45

57

Totals

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