lec9 sample

8/16/2019 Lec9 Sample

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SAMPLING PROCEDURES

MKTG 3342MKTG 3342

Fall 2008Fall 2008

Professor Edward FoxProfessor Edward Fox


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1. SAMPLING (S. CENSUS

AD(ANTAGES O! SAMPLINGAD(ANTAGES O! SAMPLING

TimeTime

C)stC)st

DISAD(ANTAGESDISAD(ANTAGES

&e*ause )nl+ a sample ,as -een&e*ause )nl+ a sample ,as -een/a0n t,e/e is ass)*iate un*e/taint+/a0n t,e/e is ass)*iate un*e/taint+

2e//)/32e//)/3


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1. SAMPLING (S. CENSUS

Ta/get P)pulati)nTa/get P)pulati)n

SampleSample


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. PROCEDURE !OR DRA"ING SAMPLE

2slig,tl+ i44e/ent 4/)m p/)*eu/e in +)u/ -))53

A. DE!INE T6E TARGET POPULATIONA. DE!INE T6E TARGET POPULATION

t,e spe*i4i*ati)n )4 pe)ple )/ *ases )n 0,)mt,e spe*i4i*ati)n )4 pe)ple )/ *ases )n 0,)m

t,e /esea/*, is t) -e *)nu*te.t,e /esea/*, is t) -e *)nu*te.&. IDENTI!$ T6E SAMPLING !RAME&. IDENTI!$ T6E SAMPLING !RAME

Listing )4 p)pulati)n elements 4/)m 0,i*,Listing )4 p)pulati)n elements 4/)m 0,i*,

sample is /a0n.sample is /a0n.C. SELECT T6E SAMPLING PLANC. SELECT T6E SAMPLING PLAN

D. DETERMINE SAMPLE SI7ED. DETERMINE SAMPLE SI7E

E. SELECT T6E SAMPLING UNITSE. SELECT T6E SAMPLING UNITS


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#. T$PES O! SAMPLING PROCEDURES

SAMPLE DESIGNSAMPLE DESIGN

NONPRO&A&ILIT$ SAMPLES NONPRO&A&ILIT$ SAMPLES PRO&A&ILIT$ SAMPLES PRO&A&ILIT$ SAMPLES

8 CON(ENIENCE8 CON(ENIENCE 8 SIMPLE RANDOM8 SIMPLE RANDOM

8 9UDGMENTAL8 9UDGMENTAL 8 STRATI!IED8 STRATI!IED8 UOTA8 UOTA PROPORTIONATEPROPORTIONATE

8 SNO"&ALL8 SNO"&ALL DISPROPORTIONATEDISPROPORTIONATE

8 CLUSTER 8 CLUSTER

8 S$STEMATIC8 S$STEMATIC


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NONPRO&A&ILIT$ SAMPLING MET6ODS

CON(ENIENCE SAMPLES

N)np/)-a-ilit+ samples use p/ima/il+ -e*ause

t,e+ a/e eas+ t) *)lle*teas+ t) *)lle*t

9UDGMENT SAMPLES

N)np/)-a-ilit+ samples in 0,i*, t,e sele*ti)n

*/ite/ia a/e -ase )n pe/s)nal


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NONPRO&A&ILIT$ SAMPLING MET6ODS

UOTA SAMPLES

N)np/)-a-ilit+ samples in 0,i*, p)pulati)n

su-g/)ups a/e *lassi4ie )n t,e -asis )4*lassi4ie )n t,e -asis )4/esea/*,e/


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PRO&A&ILIT$ SAMPLING MET6ODS SIMPLE RANDOM SAMPLING

A p/)-a-ilit+ sample in 0,i*, eve/+ element )4

t,e p)pulati)n ,as a 5n)0n an e=ual p/)-a-ilit+ )4 -eing sele*te int) t,e sample

P/)-a-ilit+ )4 Sele*ti)n >Sample Si;e

P)pulati)n Si;e


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STRATI!IED RANDOM SAMPLINGIN(OL(ES T6E !OLLO"ING T"O8STEP

PROCEDURE:

I. T,e pa/ent p)pulati)n is ivie int) mutuall+e?*lusive an *)lle*tivel+ e?,austive su-sets

2st/ata3

II. A simple /an)m sample is *,)sen 4/)m ea*,su-set

PRO&A&ILIT$ SAMPLING MET6ODS


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REASONS !OR STRATI!IED SAMPLING

88 Investigate *,a/a*te/isti*s )4 inte/est -+

su-g/)up@ st/ati4i*ati)n all)0s 4)/

ae=uate /ep/esentati)n )4 i44e/ent su-g/)ups88 In*/ease p/e*isi)n 2/eu*e sampling e//)/3

EAMPLE

Supp)se I 0ant t) investigate i4 l)08in*)me use/s e4aultm)/e )n */eit *a/ t,an ,ig,8in*)me use/s. I 0ant t)ensu/e ae=uate /ep/esentati)n )4 pe)ple 0it, -)t, ,ig,an l)0 in*)mes s) I ivie t,e p)pulati)n )n t,e -asis )4in*)me an ta5e a /an)m sample 4/)m t,e ,ig,8in*)me

g/)up an t,e l)08in*)me g/)up.


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PROPORTIONATE (S. DISPROPORTIONATEPROPORTIONATE (S. DISPROPORTIONATE

STRATI!IED SAMPLINGSTRATI!IED SAMPLING

PROPORTIONATE STRATI!IED SAMPLING: Ta5e

sample si;e in 2same3 p/)p)/ti)n t) si;e )4 t,e p)pulati)n in

ea*, su-g/)up )/ st/atum@ e.g. supp)se t,e/e a/e #BBB

,ig,8in*)me use/s an 1BBBB l)08in*)me use/s@ t,en ta5e

ma+-e #B 213 ,ig,8in*)me an lBB 213 l)08in*)me use/s

DISPROPORTIONATE STRATI!IED SAMPLING:

Sample si;e n)t ne*essa/il+ in p/)p)/ti)n t) p)pulati)n

su-g/)up si;e@ e.g. ta5e B 23 ,ig,8in*)me *)nsume/s

an 1BB 213 l)08in*)me use/s -e*ause I t,in5 t,e/e is

su-stantial va/iati)n am)ng ,ig,8in*)me *)nsume/s


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CLUSTER SAMPLINGCLUSTER SAMPLING

T"O8STEP PROCEDURE:

88 P)pulati)n is ivie int) mutuall+

e?*lusive an *)lle*tivel+ e?,austive su-sets88 A /an)m sample )4 t,e su-sets is sele*te

88 In )ne8stage *luste/ sampling all elements in

t,e /an)ml+ sele*te su-sets a/e in*lue

88 In t0)8stage *luste/ sampling a sample is

sele*te p/)-a-ilisti*all+ 4/)m ea*, /an)ml+

sele*te su-set


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MOTI(ATION !OR CLUSTER SAMPLINGMOTI(ATION !OR CLUSTER SAMPLING

GENERALL$ LO"ER COST 2-ut less a**u/ate3

!)/ e?ample

In t,e in*)me */eit e4ault *ase supp)se +)u ivie pe)ple -ase )n 0,e/e t,e+ live 2sa+ -+ ;ip *)e3 t,en /an)ml+ sele*t

;ip *)es 2sa+ F'% an F'13 an investigate eit,e/ eve/+)ne

in -)t, ;ip *)es )/ a /an)m sample )4 pe)ple 4/)m -)t, ;ip

*)es


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DI!!ERENCE &ET"EEN STRATI!ICATIONDI!!ERENCE &ET"EEN STRATI!ICATION

AND CLUSTERINGAND CLUSTERING

T,e va/ia-le use 4)/ st/ati4i*ati)n must -e /elate t) /esea/*,must -e /elate t) /esea/*,

4)*us4)*us 2in*)me in )u/ e?ample3

T,e va/ia-le use 4)/ *luste/ing mustmust n)tn)t -e /elate t) /esea/*, -e /elate t) /esea/*,4)*us4)*us 2;ip *)e in )u/ e?ample3


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PRO&A&ILIT$ SAMPLING MET6ODS

S$STEMATIC SAMPLING

P/)-a-ilit+ sampling in 0,i*, t,e enti/e

p)pulati)n is num-e/e. T,e 4i/st num-e/ is/a0n /an)ml+. Su-se=uent elements a/e

/a0n using a s5ip inte/val.

S5ip Inte/val > P)pulati)n Si;e

Sample Si;e


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SUMMAR$ O! JE$ POINTS

21 )4 3

T,e p)pulati)n is t,e t)tal g/)up )4 pe)ple

in 0,)se )pini)ns )ne is inte/este

A *ensus inv)lves *)lle*ting esi/e

in4)/mati)n 4/)m all t,e mem-e/s )4 t,e

p)pulati)n

A sample is simpl+ a su-set )4 a p)pulati)n


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SUMMAR$ O! JE$ POINTS

2 )4 3

P/)-a-ilit+ sampling met,)s a/e sele*te in su*,

a 0a+ t,at eve/+ element )4 t,e p)pulati)n ,as a

5n)0n n)n;e/) p/)-a-ilit+ )4 sele*ti)n N)np/)-a-ilit+ sampling met,)s in*lue all

met,)s t,at sele*t spe*i4i* elements 4/)m t,e

p)pulati)n in a n)n/an)m manne/

St/ati4ie p/)-a-ilit+ sampling is gene/all+ t,e -est

met,) 4)/ sele*ting a sample i4 time an -uget

pe/mit

lec9 sample

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