AICP Exam Review Statistics/Methods Questions and Answers

AICP Exam Review
Statistics/Methods Questions and
Answers
InferentialAStatisticsA-
AAnswerAUsingAinformationAfromAsamplesAtoAmakeAinferencesAaboutApopulatio
ns;APopulation:AtheAtotalAcollectionAofAallAcasesAinAwhichAtheAresearcherAisAin
terestedAandAwishesAtoAunderstand


EqualAProbabilityAofASelectionAMethodA(EPSEM)A-
AAnswerAAKA:ArandomAselection;ATwoAconditions:A1)AeachAcaseAinAaApopulatio
nAhasAaAknownAprobabilityAofAselectionA2)AeachAcaseAinAaApopulationAhasAan
AequalAprobabilityAofAselection;ATheoretical,AinApracticeAthisAisAnotAreallyAposs
ible


ProbabilityASamplingA-
AAnswerAAnyAsamplingAthatAusesAEPSEM/randomAselection;AMainAadvantages:
AavoidsAsystematicAbiasAandAmoreAlikelyAtoAproduceArepresentativeAsamplesAt
hatAhaveAlessAsamplingAerrorAandAwhereAtheAmarginAofAerrorAcanAbeAestimat
ed;ACanAreduceAtheAmarginAofAerrorAwithAbiggerAsampleAsizesAandAbyAstudyin
gAaAmoreAhomogeneousApopulation;ADisadvantages:AmoreAcostly,AtimeAconsumi
ng,AandAcomplex;AExamples:ASimpleArandom,AsystematicArandom,AstratifiedAra
ndom,Acluster


Non-ProbabilityASamplingA-
AAnswerASamplingAthatAdoesAnotAuseAEPSEM/randomAselection;AMainAadvanta
ges:AcheaperAandAquicker;ADisadvantages:AbecauseAelementsAinApopulationAdoA
notAhaveAequalAchancesAofAbeingAselectedAthereAisAlessAgeneralizability;AExam
ples:Aavailability/convenienceAsampling;ApurposiveAsampling,AsnowballAsamplin
g


DescriptiveAStatisticsA-AAnswerADataAreductionA-
AbasedAonAsamples;ADataAreduction:AsummarizingAmanyAincidences/scoresAwith
AaAfewAstatisticsA(e.g.AmeasuresAofAdispersionA&AmeasuresAofAcentralAtendency
)

, StatisticAvs.AParameterA-
AAnswerAStatistic:AInfoAthatAcomesAfromAaAsample,AusedAasAestimatesAforApar
ameters
Parameter:ATrueAvalueAforAaAstatisticAinAtheAentireApopulation
*ThereAwillAbeAveryAlittleAdifferenceAbetweenAtheseAtwoAifAsamplingAisAdoneAr
igorously


EstimateA-
AAnswerAMeasureAofAaApresent/pastAconditionAthatAcannotAbeAmeasuredAdirect
lyAdueAtoAlackAofAtimeAandAotherAresources;AForAexample:AaApopulationAestim
ateAfromAautoAorAvoterAregistration


ThroughputAIndexA-
AAnswerAMeasureAofAgrossAchangeAinApopulationAmembershipAoverAtime;A>10
0AisAhighA"churning"Apopulation;A<100AindicatesAaAmoreAstableApopulation


NormalA(symmetric)AdistributionA-
AAnswerATheAmean,Amedian,AandAmodeAareAallAsimilar;AAKAAstandardABellAC
urve


StandardADeviationA-
AAnswerAHowAmuch,AonAaverage,AeachA"score"/incidenceAdiffersAfromAtheAmea
n;AUsedAforAnormalAdistributionsAonly


ZAScoreA-
AAnswerATheAnumberAofAstandardAdeviationsAaAscore/incidenceAisApositionedAf
romAtheAmeanAofAaAnormalAcurve;A"Standardized"AscoreAforAuseAinAcalculatin
gApercentiles


ProjectionA-
AAnswerAAAconditionalAstatementAaboutAtheAfuture,AdescribingAwhatAtheAfuture
AisAlikelyAtoAbeAifAaAgivenAsetAofAassumptionsAprovesAtoAbeAtrue;AForAexamp
le:AaAtotalAcommunityApopulationAwillAincreaseAbyA30%AinAtheAnextAdecadeAif
AcurrentAcommunityAgroupAtrendsAcontinue;AUncertaintyAinAprojectionsAincrease
sAwithAlongerAprojectedAtimeAframesAandAsmallerAgeographicalAareas