数据分析习题11.docx
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数据分析习题11.docx
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数据分析习题11
Question1
Whichofthefollowingclassificationsofvariabletypesisfalse?
YourAnswer
Score
Explanation
Studentheight→continuousnumerical
PopulationofeachstateintheUS→continuousnumerical
Correct
1.00
Counteddataarediscretenumericalvariablessincetheycan’ttakeonnon-wholevalues.
Customersatisfaction:
veryunsatisfied,unsatisfied,satisfied,verysatisfied→ordinalcategorical
Whetherastudenthaspreviouslytakenastatisticscourse→categorical
Total
1.00/1.00
QuestionExplanationThisquestionreferstothefollowinglearningobjective(s):
Identifyvariablesasnumericalandcategorical.
•Ifvariableisnumerical,furtherclassifyascontinuousordiscretebasedonwhetherornotthevariablecantakeonaninfinitenumberofvaluesoronlynon-negativewholenumbers,respectively.
•Ifvariableiscategorical,determineifitisordinalbasedonwhetherornotthelevelshaveanaturalordering.
Question2
Astudyisdesignedtotesttheeffectoftypeoflightonexamperformanceofstudents.180studentsarerandomlyassignedtothreeclassrooms:
onethatisdimlylit,anotherwithyellowlighting,andathirdwithwhitefluorescentlighting,andgiventhesameexam.Whichofthefollowingcorrectlyidentifiesthevariablesusedinthestudyasexplanatoryandresponse?
YourAnswer
Score
Explanation
explanatory:
examperformance
response:
typeoflight(categoricalwith3levels)
explanatory:
dimlylit,yellow,whitefluorescent
response:
examperformance
explanatory:
examperformance
response:
dimlylit,yellow,whitefluorescent
explanatory:
typeoflight(categoricalwith3levels)
response:
examperformance
Correct
1.00
Weareinterestedintheeffectoftypeoflightonexamperformance,thereforetypeoflightistheexplanatoryvariableandexamperformanceistheresponsevariable.Typeoflightisacategoricalvariablethatcantakeonthreepossiblevalues(dimlylit,yellowlight,whitelight).Thesepossiblevaluesarecalledlevels.
Total
1.00/1.00
QuestionExplanationThisquestionreferstothefollowinglearningobjective(s):
Identifytheexplanatoryvariableinapairofvariablesasthevariablesuspectedofaffectingtheother,howevernotethatlabelingvariablesasexplanatoryandresponsedoesnotguaranteethattherelationshipbetweenthetwoisactuallycausal,evenifthereisanassociationidentifiedbetweenthetwovariables.
Question3
TrueorFalse:
Ifsubjectsarerandomlyassignedtotreatments,conclusionscanbegeneralizedtothepopulation.
YourAnswer
Score
Explanation
False
True
Inorrect
0.00
Randomassignmentallowsustomakecausalconclusions.Forgeneralizability,weneedrandomsampling.
Total
0.00/1.00
QuestionExplanationThisquestionreferstothefollowinglearningobjective(s):
Classifyastudyasobservationalorexperimental,anddeterminewhetherthestudy’sresultscanbegeneralizedtothepopulationandwhethertheysuggestcorrelationorcausation.
•Ifrandomsamplinghasbeenemployedindatacollection,theresultsshouldbegeneralizabletothetargetpopulation.
•Ifrandomassignmenthasbeenemployedinstudydesign,theresultssuggestcausality.
Question4
Anextraneousvariablethatisrelatedtotheexplanatoryandresponsevariablesandthatpreventsusfromdeducingcausalrelationshipsbasedonobservationalstudiesiscalleda.
AnswerforQuestion4Youentered:
YourAnswer
Score
Explanation
Incorrect
0.00
Total
0.00/1.00
QuestionExplanationThisquestionreferstothefollowinglearningobjective(s):
Questionconfoundingvariablesandsourcesofbiasinagivenstudy.
Question5
Aspartofastatisticsproject,Andreawouldliketocollectdataonhouseholdsizeinhercity.Todoso,sheaskseachpersoninherstatisticsclassforthesizeoftheirhousehold,andreportsthathersampleisasimplerandomsample.However,thisisnotasimplerandomsample.Whichofthefollowingisthebestreasoningforwhythisisnotarandomsamplethatisappropriateforthisresearchquestion?
YourAnswer
Score
Explanation
Andreadidnotuseanyrandomization;shetookaconveniencesample.
Correct
1.00
Andreadidnotuseastratifiedsample.
Andreadidnotusearandomnumbertabletorandomizetheorderinwhichshecollectedthestudents’responses,sothesamplecannotberandom.
Andreaaskedeverybodyinherclassinsteadofaskingherclassmatestovolunteer.
Total
1.00/1.00
QuestionExplanationThisquestionreferstothefollowinglearningobjective(s):
Distinguishbetweensimplerandom,stratified,andclustersampling,andrecognizethebenefitsanddrawbacksofchoosingonesamplingschemeoveranother.
Question6
Whichofthefollowingisoneofthefourprinciplesofexperimentaldesign?
YourAnswer
Score
Explanation
stratify
cluster
block
Correct
1.00
Thefourprinciplesofexperimentaldesignarecontrol,randomize,replicate,andblock.
non-response
Total
1.00/1.00
QuestionExplanationThisquestionreferstothefollowinglearningobjective(s):
Identifythefourprinciplesofexperimentaldesignandrecognizetheirpurposes:
∙controlanypossibleconfounders,
∙randomizeintotreatmentandcontrolgroups,
∙replicatebyusingasufficientlylargesampleorrepeatingtheexperiment,
∙blockanyvariablesthatmightinfluencetheresponse.
Question7
Whichofthebelowdatasetshasthehigheststandarddeviation?
Youdonotneedtocalculatetheexactstandarddeviationstoanswerthisquestion.
YourAnswer
Score
Explanation
0,25,25,25,25,25,25
0,1,2,3,4,5,6
0,100,200,300,400,500,600
Correct
1.00
Thedatasetwiththeleastrepeatedobservationsthatarefarthestfromthecenterhasthemostvariability,hencethehigheststandarddeviation.
0,1,1,1,1,1,2
Total
1.00/1.00
QuestionExplanationThisquestionreferstothefollowinglearningobjective(s):
Notethattherearethreecommonlyusedmeasuresofcenterandspread:
∙center:
mean(thearithmeticaverage),median(themidpoint),mode(themostfrequentobservation)
∙spread:
standarddeviation(variabilityaroundthemean),range(max-min),interquartilerange(middle50%ofthedistribution)
Question8
Thedistributionofhousingpricesinacountrywhere25%ofthehousescostbelow$350,000,50%ofthehousescostbelow$450,000,75%ofthehousescostbelow$1,000,000andthereareameaningfulnumberofhousesthatcostmorethan$6,000,000ismostlikely
YourAnswer
Score
Explanation
leftskewed
rightskewed
Correct
1.00
Thereisalongtailontherightsideofthedistribution,yieldingarightskew.
uniform
symmetric
Total
1.00/1.00
QuestionExplanationThisquestionreferstothefollowinglearningobjective(s):
Identifytheshapeofadistributionassymmetric,rightskewed,orleftskewed,andunimodal,bimodoal,multimodal,oruniform.
Question9
Twodistributions(AandB)areshownontheboxplotbelow.Whichofthefollowingstatementsisnotsupportedbytheplot?
YourAnswer
Score
Explanation
Bothdistributionsareunimodal.
MedianofAishigherthanmedianofB.
BismorevariablethanA.
Bothdistributionsareroughlysymmetric.
Inorrect
0.00
Bothboxesdoappeartobesymmetric.
Total
0.00/1.00
QuestionExplanationThisquestionreferstothefollowinglearningobjective(s):
Usehistogramsandboxplotstovisualizetheshape,center,andspreadofnumericaldistributions,andintensitymapsforvisualizingthespatialdistributionofthedata.
Question10
Arecenthousingsurveywasconductedtodeterminethepriceofatypicalhomeinacitythatismostlymiddle-class,withoneveryexpensivesuburb.Themeanpriceofahouseinthiscityisroughly$650,000.Whichofthefollowingstatementsismostlikelytobetrue?
YourAnswer
Score
Explanation
Weneedtoknowthestandarddeviationtoanswerthisquestion
Thereareaboutasmanyhousesinthiscitythatcostmorethan$650,000thanlessthanthisamount.
Majorityofhousesinthiscitycostmorethan$650,000.
Majorityofhousesinthiscitycostlessthan$650,000.
Correct
1.00
Sincethecityismostlymiddle-class,withoneveryexpensivesuburb,wewouldexpectthedistributiontoberightskewed,andthereforethemeantobegreaterthanthemedian.Since50%ofobservationsfallbelowthemedian,morethan50%ofobservations(i.e.majority)willcostlessthan$650,000,themean.
Total
1.00/1.00
QuestionExplanationThisquestionreferstothefollowinglearningobjective:
Definearobuststatistic(e.g.median,IQR)asastatisticsthatisnotheavilyaffectedbyskewnessandextremeoutliers,anddeterminewhensuchstatisticsaremoreappropriatemeasuresofcenterandspreadcomparedtoothersimilarstatistics.
Question11
Itisrelativelycommonforfishtobemislabeledinsupermarketsandeveninrestaurants.Thetablebelowshowstheresultsofastudywherearandomsampleof156fishforsalewerecollectedandgeneticallytested.Theresearchersclassifiedeachsampleasbeinglabeledproperlyorbeingmislabeled.Whatfractionofsmokedfishinthesampleweremislabeled?
Choosetheclosestanswer.
YourAnswer
Score
Explanation
28%
9%
72%
Inorrect
0.00
Lookamongonlythesmokedfish,andfindtheproportionofthosethataremislabeled.
18%
78%
Total
0.00/1.00
QuestionExplanationThisquestionreferstothefollowinglearningobjective(s):
Usecontingencytablesandsegmentedbarplotsormosaicplots
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- 数据 分析 习题 11