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statistics20bykeller

CHAPTER20

TIME-SERIESANALYSISANDFORECASTING

SECTIONS1-2

MULTIPLECHOICEQUESTIONS

Inthefollowingmultiple-choicequestions,pleasecirclethecorrectanswer.

1.Atimeseriesis:

a.asetofmeasurementsonavariablecollectedatthesametimeorapproximatelythesameperiodoftime.

b.asetofmeasurementsonavariabletakenoversometimeperiodinsequentialorder

c.amodelthatattemptstoanalyzetherelationshipbetweenadependentvariableandoneormoreindependentvariables

d.amodelthatattemptstoforecastthefuturevalueofavariable

ANSWER:

b

2.Thetimeseriescomponentthatreflectsalong-term,relativelysmoothpatternordirectionexhibitedbyatimeseriesoveralongtimeperiod（morethanoneyear）iscalled:

a.long–termtrend

b.cyclicalvariation

c.seasonalvariation

d.randomvariation

ANSWER:

a

3.Thetimeseriescomponentthatreflectsvariabilityovershortrepetitivetimeperiodsandhasdurationoflessthanoneyeariscalled:

a.long–termtrend

b.cyclicalvariation

c.seasonalvariation

d.randomvariation

ANSWER:

c

4.Thetimeseriescomponentthatreflectstheirregularchangesinatimeseriesthatarenotcausedbyanyothercomponent,andtendstohidetheexistenceoftheothermorepredictablecomponents,iscalled:

a.long–termtrend

b.cyclicalvariation

c.seasonalvariation

d.randomvariation

ANSWER:

d

5.Whichofthefour-timeseriescomponentismorelikelytoexhibitthechangesinstockmarketpricesatparticulartimesduringthecourseofoneday?

a.Long–termtrend

b.Cyclicalvariation

c.Seasonalvariation

d.Randomvariation

ANSWER:

c

6.Theterm“seasonalvariation”mayreferto:

a.thefourtraditionalseasons

b.systematicpatternsthatoccurduringtheperiodofoneweek

c.systematicpatternsthatoccuroverthecourseofoneday

d.Alloftheabove

ANSWER:

d

7.WhichofthefourtimeseriescomponentsismorelikelytoexhibittherelativesteadygrowthofthepopulationofEgyptfrom1964to2004?

a.Long–termtrend

b.Cyclicalvariation

c.Seasonalvariation

d.Randomvariation

ANSWER:

a

8.Thetimeseriescomponentthatreflectsawavelikepatterndescribingalong-termtrendthatisgenerallyapparentoveranumberofyearsiscalled:

a.long–termtrend

b.cyclicalvariation

c.seasonalvariation

d.randomvariation

ANSWER:

b

9.Wecalculatethethree-periodmovingaveragesforatimeseriesforalltimeperiodsexceptthe:

a.firstperiod

b.lastperiod

c.firstandlastperiod

d.firstandlasttwoperiods

ANSWER:

c

10.Wecalculatethefive-periodmovingaverageforatimeseriesforalltimeperiodsexceptthe:

a.firstfiveperiods

b.lastfiveperiods

c.firstandlastperiod

d.firsttwoandlasttwoperiods

ANSWER:

d

11.Inexponentiallysmoothedtimeseries,thesmoothingconstantwischosenonthebasisofhowmuchsmoothingisrequired.Ingeneral,whichofthefollowingstatementsistrue?

a.Asmallvalueofwsuchasw=0.1resultsinverylittlesmoothing,whilealargevaluesuchasw=0.8resultsintoomuchsmoothing

b.Asmallvalueofwsuchasw=0.1resultsintoomuchsmoothing,whichalargevaluesuchasw=0.8resultsinverylittlesmoothing

c.Asmallvalueofwsuchasw=0.1andalargevaluesuchasw=.8maybothresultinverylittlesmoothing

d.Asmallvalueofwsuchasw=0.1andalargevaluesuchasw=0.8maybothresultintoomuchsmoothing

ANSWER:

b

12.Inmeasuringthecyclicaleffectofatimeseries,cyclesneedtobeisolated.Themeasureweusetoidentifycyclicalvariationisthe:

a.meanabsolutedeviation

b.trendvalue

c.percentageoftrend

d.ratioofthetimeseriesdividedbythemovingaverage

ANSWER:

c

13.Ifwewanttomeasuretheseasonalvariationsonstockmarketperformancebyquarter,wewouldneed:

a.4indicatorvariables

b.3indicatorvariables

c.2indicatorvariables

d.1indicatorvariable

ANSWER:

b

14.Thenumberoffour-periodcenteredmovingaveragesofatimeserieswith20timeperiodsis:

a.28

b.24

c.20

d.16

ANSWER:

d

15.Ingeneral,itiseasytoidentifythetrendcomponentofatimeseriesbyusing:

a.exponentialsmoothing

b.movingaverages

c.regressionanalysis

d.seasonallyadjustedtimeseries

ANSWER:

c

16.Inmeasuringseasonalandrandomvariationofatimeserieswithnocyclicaleffect,wemayusethe:

a.ratioofthetimeseriesdividedbythemovingaverage

b.ratioofthetimeseriesdividedbythepredictedvalues

c.trendvalue

d.Both（a）and（b）

ANSWER:

d

17.Whichofthefollowingstatementsisfalse?

a.Amovingaverageforatimeperiodisthesimplearithmeticaverageofthevaluesinthattimeperiodandthoseclosetoit.

b.Avalueofthesmoothingconstantwcloseto1resultsinaverylargesmoothing,whereasavalueofwclosetozeroresultsinverylittlesmoothing.

c.Theaccuracyoftheforecastwithexponentialsmoothingdecreasesrapidlyforpredictionsofthetimeseriesmorethanoneperiodintothefuture.

d.Amovingaverage“forgets”mostoftheprevioustime-seriesvaluesandisconsideredarelativelycrudemethodofremovingtherandomvariation.

ANSWER:

b

18.Ifwewanttomeasuretheseasonalvariationsonstockmarketperformancebymonth,wewouldneed:

a.50indicatorvariablessincethestockmarkethasa5-dayworkperweek

b.12indicatorvariablestorepresentthe12months

c.11indicatorvariables

d.52indicatorvariables

ANSWER:

c

19.Thestockmarkethasa5-dayworkperweek.Ifwewanttomeasuretheimpactofthedayoftheweekonstockmarketperformancewewouldneed:

a.7indicatorvariables

b.6indicatorvariables

c.5indicatorvariables

d.4indicatorvariables

ANSWER:

d

20.Ifdataforatimeseriesanalysisarecollectedonamonthlybasisonly,whichcomponentofthetimeseriesmaybeignored?

a.Long-termtrend

b.Cyclicalvariation

c.Seasonalvariation

d.Randomvariation

ANSWER:

c

21.Thetime-seriesmodel

isusedforforecasting,where

and

arerespectivelythetrend,cyclical,seasonal,andrandomvariationcomponentsofthetimeseries,and

isthevalueofthetimeseriesattimet.Thefollowingestimatesareobtained:

Themodelwillproduceaforecastof:

a.122.870

b.104.652

c.116.280

d.102.600

ANSWER:

b

22.Whichofthefollowingmethodsisappropriateforforecastingatimeserieswhenthetrend,cyclical,andseasonalcomponentsoftheseriesarenotsignificant?

a.Movingaverages

b.Exponentialsmoothing

c.Meanabsolutedeviation

d.Seasonalindexes

ANSWER:

a

23.Whichofthefollowingisnottrueinregardtotheweightsusedinexponentialsmoothing?

a.Thelastweightisalwaysthesmallest

b.Theyareallpositive

c.Theyaddupto1.

d.Theydecreaseexponentiallyintothepast

ANSWER:

a

24.Theformula

isusedintime-seriesforecastingwithexponentialsmoothing,where

istheexponentiallysmoothedtimeseriesattimet,

isthevalueofthetimeseriesattimet,andwisthesmoothingconstant.Theforecastedvalueattimet+1wherew=.4isgivenby:

a.

b.

c.

d.

ANSWER:

c

25.Thetrendline

wascalculatedfromquarterlydatafor2000–2004,wheret=1forthefirstquarterof2000.Thetrendvalueforthesecondquarteroftheyear2005is:

a.0.705

b.0.820

c.0.815

d.0.810

ANSWER:

d

26.Thefollowingarethevaluesofatimeseriesforthefirstfourtimeperiods:

t

1

2

3

4

23

25

28

24

Usingafour-periodmovingaverage,theforecastedvaluefortimeperiod5is:

a.25.3

b.25.7

c.25.0

d.26.0

ANSWER:

c

27.Thelineartrend

wasestimatedusingatimeserieswith25timeperiods.Theforecastedvaluefortimeperiod26is:

a.180.8

b.178.3

c.175.8

d.Notenoughinformationisgiventoanswerthequestion

ANSWER:

a

28.Supposethatwecalculatethefour-periodmovingaverageofthefollowingtimeseries

t

1

2

3

4

5

6

16

28

21

15

26

12

Thecenteredmovingaverageforperiod3is:

a.22.5

b.21.25

c.20.50

d.18.5

ANSWER:

b

29.Theeffectofanunpredictable,rareeventwillbecontainedinwhichcomponentofthetimeseries?

a.Long–termtrend

b.Cyclicalvariation

c.Seasonalvariation

d.RandomVariation

ANSWER:

d

30.Themodel

thatassumesthetimeseriesvalueattimetisthesumofthefourtimeseriescomponents

isreferredtoas:

a.additivemodel

b.multiplicativemodel

c.movingaveragesmodel

d.forecastmodel

ANSWER:

a

31.Themodel

thatassumesthetimeseriesvalueattimetistheproductofthefourtimeseriescomponentsisreferredtoas:

a.additivemodel

b.forecastmodel

c.movingaveragesmodel

d.multiplicativemodel

ANSWER:

d

32.Smoothingtimeseriesdatabythemovingaveragemethodorexponentialsmoothingmethodisanattempttoremovetheeffectofthe:

a.trendcomponent

b.cyclicalcomponent

c.seasonalcomponent

d.randomvariationcomponent

ANSWER:

d

33.Thehighlevelofairlineticketsalesthattravelagenciesexperienceduringsummerisanexampleofwhatcomponentofatimeseries?

a.Long–termtrend

b.Cyclicalvariation

c.Seasonalvariation

d.Randomvariation

ANSWER:

b

34.Forwhichofthefollowingvaluesofthesmoothingconstantwwillthesmoothedseriescatchupmostquicklywhenevertheoriginaltimeserieschangesdirection?

a.0.90

b.0.50

c.0.40

d.0.10

ANSWER:

a

35.Thefollowingarethevaluesofatimeseriesforthefirstfourtimeperiods:

t

1

2

3

4

23

25

28

24

Usingexponentialsmoothing,withw=0.30,theforecastedvaluefortimeperiod5is:

a.24.920

b.24.644

c.23.600

d.23.000

ANSWER:

b

36.Whichofthefollowingsmoothingconstantscausesthemostrapidreactiontoachangeinthecurrenttimeseriesvalue?

a.0.40

b.0.30

c.0.20

d.0.10

ANSWER:

a

37.Theoverallupwardordownwardpatternofthed