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1、SampleSurveyChapter21SampleSurveyLearningObjectives1.Learnwhatasamplesurveyisandhowitdiffersfromanexperimentasamethodofcollectingdata.2.Knowaboutthemethodsofdatacollectionforasurvey.3.Knowthedifferencebetweensamplingandnonsamplingerror.4.Learnaboutfours
2、ampledesigns:(1)simplerandomsampling,(2)stratifiedsimplerandomsampling,(3)clustersampling,and(4)systematicsampling.5.Leanhowtoestimateapopulationmean,apopulationtotal,andapopulationproportionusingtheabovesampledesigns.6.Understandtherelationshipbetweens
3、amplesizeandprecision.7.Learnhowtochoosetheappropriatesamplesizeusingstratifiedandsimplerandomsampling.8.Learnhowtoallocatethetotalsampletothevariousstratausingstratifiedsimplerandomsampling.21-19SampleSurveySolutions:1.a.=215isanestimateofthepopulation
4、mean.b.c.215±2(2.7386)or209.5228to220.47722.a.Estimateofpopulationtotal=N=400(75)=30,000b.EstimateofStandardError=c.30,000±2(320)or29,360to30,6403.a.=.30isanestimateofthepopulationproportionb.c..30±2(.0437)or.2126to.38744.B=15Asamplesizeof73willprovidea
5、napproximate95%confidenceintervalofwidth30.5.a.=149,670ands=73,420approximate95%confidenceinterval149,670±2(10,040.83)or$129,588.34to$169,751.66b.=N=771(149,670)=115,395,570=N=771(10,040.83)=7,741,479.9321-19SampleSurveyapproximate95%confidenceinterval1
6、15,395,770±2(7,741,479.93)or$99,912,810.14to$130,878,729.86c.=18/50=0.36andapproximate95%confidenceinterval0.36±2(0.0663)or0.2274to0.4926Thisisaratherlargeinterval;samplesizesmustberatherlargetoobtaintightconfidenceintervalsonapopulationproportion.6.B=5
7、000/2=2500Usethevalueofsforthepreviousyearintheformulatodeterminethenecessarysamplesize.Asamplesizeof337willprovideanapproximate95%confidenceintervalofwidthnolargerthan$5000.7.a.Stratum1:=138Stratum2:=103Stratum3:=210b.Stratum1=138138±2(6.3640)or125.272
8、to150.728Stratum2=10321-19SampleSurvey103±2(4.2817)or94.4366to111.5634Stratum3=210210±2(8.6603)or192.6794to227.3206c.=50.1818+46.8182+38.1818=135.1818approximate95%confidenceinterval135.1818±2(3.4092)or128.3634to142.00028.a.Strat