2 Stage Cluster Sampling - Survey Sampling Techniques - Lecture Slides, Slides of Survey Sampling Techniques

Survey Sampling Techniques course is one of important courses in Statisitics. Major poiuts of this course are: probability sampling, confidence intervals, Two-stage cluster sampling, Two-stage cluster sampling, estimation for mean, choosing strata, allocation across strata, ratio estimation, domain estimation, Two-stage cluster sampling. Keywords in these slides are: 2 Stage Cluster Sampling, Primary Sampling Unit, Secondary Sampling Unit, 1-Stage Cluster, Notation, Cluster-Level, Complete Enume

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2012/2013

Uploaded on 08/30/2013

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2-stage cluster sampling with equal
selection probs
Overview
Process
Stage 1: select clusters
Stage 2: select elements within each sampled cluster
First stage sampling unit is a …
PSU = primary sampling unit = cluster
Second stage sampling unit is a …
SSU = secondary sampling unit = element
Only collect data on the SSUs that were sampled from the
cluster
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2-stage cluster sampling with equal

selection probs

  • Overview
    • Process
      • Stage 1: select clusters
      • Stage 2: select elements within each sampled cluster
    • First stage sampling unit is a …
      • PSU = primary sampling unit = cluster
    • Second stage sampling unit is a …
      • SSU = secondary sampling unit = element
    • Only collect data on the SSUs that were sampled from the cluster

1-stage vs. 2-stage cluster sampling

Sample all SSUs in sampled PSUs: Take an SRS ofmi SSUs in sampled PSUi :

1-stage cluster sample (stop here)

Stage 1 of 2-stage cluster sample (select PSUs)

Stage 2 of 2-stage cluster sample (select SSUs w/in PSUs)

Now we have to estimate cluster-level

pop. parameters

  • For 1-stage cluster samples
    • Have a complete enumeration of the cluster elements
    • Cluster population parameters are known
      • Directly observe , tiU , piU
  • For 2-stage cluster samples
    • Observe data on a sample of elements in a cluster
    • Estimate cluster population parameters
      • Calculate estimates of , tiU , piU

yiU

yiU

Motivation for 2-stage cluster samples

  • Recall most common motivations for cluster

sampling

  • Only have access to a frame that lists clusters
  • Reduce data collection costs by going to groups of

nearby elements (cluster defined by proximity)

CSE2 unbiased estimation for

population total t

  • Have a sample of elements from a cluster
    • We no longer know the value of cluster

parameter, tiU

  • Estimate tiU using data observed for mi

elements

 

 

m i

j

ij i

i i i i^ y m

M t M y 1

ˆ

CSE2 unbiased estimation for

population total

  • Approach is to plug estimated cluster totals

into CSE1 formula

  • CSE
  • CSE

   

n

i

i i

n

j

unb i n M^ y

N t n

N t 1 1

   

n

i

i iU

n

j

unb iU n M^ y

N t n

N t 1 1

CSE2 unbiased estimation for

population total

  • In CSE1, we observe all elements in a cluster
    • We know ti
    • Have variance component 1, but no component 2
  • In CSE2, we sample a subset of elements in a cluster
    • We estimate ti with
    • Component 2 is a function of estimates variance for

tˆi

tˆi

i

i i

i i m

s M

m M

2 (^2 ) 

 

 

 

 

CSE2 unbiased estimation for

population total

  • Estimated variance among cluster totals
  • Estimated variance among elements within a

single cluster i

  

 

 

 

  

n

i

t i unb N

t t n

s 1

2 (^2) ˆ ˆ 1

1

^  

m i

j

ij i i

s (^) i m y y 1

2 2 1

Dorm example

  • Stage 2: select 2 students in each room

Stu-

dent

Rm

Rm

Rm

Rm

Rm

Total?????

Dorm example

  • Stage 1
    • Cluster =
    • N =
    • n =
    • SRSWOR
  • Stage 2
    • Element =
    • Mi =
    • mi =
    • SRSWOR

tˆi

Dorm example

tˆi

Stu- dent (j)

Rm 6 (i=1)

Rm 21 (i=2)

Rm 28 (i=3)

Rm 54 (i=4)

Rm 89 (i=5)

5.5 2.5 4.5 4.5 3. 22 10 18 18 12 si^2 0.5 0.5 0.5 0.5 2.

yi Mi y i 

 ^ i ^  ^ 

m m (^) i j 1 yij^ yi

2 1

1

Dorm example

 (^)   

n

j

unb n^ ti

N t 1

  

 

 

  

 (^)  

n

i

unb t i N

t t n

s 1

2 (^2) ˆ ˆ 1

1

CSE2 unbiased estimation for

population mean

 

  2

ˆ ˆ ˆ^ ˆ

K

V t

V y

K

t

y

unb unb

unb unb

yU

Dorm example

2

K

V t V y

K

t y

unb unb

unb unb