Matakuliah
Tahun
Versi
: MN J0412/ Riset Pemasaran
: 2007
:
Pertemuan Kesembilan
Sampling and Data Collection
1
Learning Outcomes
Pada akhir pertemuan ini, diharapkan mahasiswa
akan mampu :
• Mahasiswa dapat menyisihkan sampel
dan populasi tanpa menghilangkan unsur
2
Outline Materi
•
•
•
•
•
Materi 1: Required Steps in Sampling
Materi 2: Types of Sampling Plans
Materi 3: Non Probability Samples
Materi 4:Probability Samples
Materi 5: Sample Size
3
6-Step Procedure for Drawing a Sample
Step 1
Define the Target Population
Step 2
Identify the Sampling Frame
Step 3
Select a Sampling Procedure
Step 4
Determine the Sample Size
Step 5
Select the Sample Elements
Step 6
Collect the Data from the
Designated Elements
4
Classification of Sampling Techniques
Sampling Designs
Probability Samples
•Simple Random
Nonprobability Samples •Statified
•Convenience
•Proportionate
•Judgment
•Disproportionate
•Quota
•Cluster
•Systematic
•Area
5
Distribution of Sample Means for Different Samples Sizes, Population Shapes
Populations
n=2
Sampling
Distributions
of mean
n=5
n = 30
6
Relationship Between Parameters of Parent Population and Derived Population
Parent Population
Element
Mean:

=
Variance: 2 =
Total
A
3
B
6
C
9
D
12
E
15
F
18
 Xi
3 + 6 + 9 + 12 + 15 + 18
=
=
N
6
10.5
 (Xi-)2
(3-10.5)2 + ... +(18-10.5)2
=
N
6
= 157.5 = 26.25
6
7
Derived Population of All Possible Distinguishable Samples
Element
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
ABC
ABD
ABE
ABF
ACD
ACE
ACF
ADE
ADF
AEF
BCD
BCE
BCF
BDE
BDF
BEF
CDE
CDF
CEF
DEF
Total
18
21
24
27
24
27
30
30
33
36
27
30
33
33
36
39
36
39
42
45
Mean Xj
6
7
8
9
8
9
10
10
11
12
9
10
11
11
12
13
12
13
14
15
8
Derived Population
L
 xj
Mean:
j =1
E( x ) = x =
L
Variance: _2
x
=
6 + 7 + ... + 15
20
105
= 10.5
=
20
L
 ( xj - E(x))2
j =1
L
=(6 -10.5)2 + (7-10.5)2 + ... + (15-10.5)2
20
= 5.25
9
Distribution of Variables in Parent and Derived Population
1
Absolute
Frequency
0
1
3
5
7
9 11 13 15 17
Values of X
1
3
5
7
9 11 13 15 17
Values of x
3
2
Absolute
Frequency
1
0
10
Example Calculations of Generating a Confidence Interval with a Stratified Sample
I
II
n1 = 100
x1 =
^
s12 =
 Xi1
n1
n2 = 100
x2 =
= 3.2
 (Xi1 x1 )2
= .14
n1 -1
^
s22 =
III
^
s32 =
 Xi3
n3
= 4.6
 (Xi2 x2 )2
= .12
n2 -1
IV
n3 = 100
x3 =
 Xi2
n2
n4 = 100
= 5.8
 (Xi3 x3 )2
= .20
n3 -1
x4 =
^
s42 =
 Xi4
n4
= 7.2
 (Xi4 x4 )2
= .18
n4 -1
11
Size and Strata in Parent Population
I.
N1 =
5000
II.
N2 =
25000
III.
N3 =
15000
IV.
N4 =
5000
N = 50000
L
xst

h=1
=
Whxh
Nhxh

h=1
L
=
N
= 1/10(3.2) + 5/10(4.6) + 3/10(5.8) + 1/10(7.2) = 5.08
2
L
sx2st =

h=1
Whs2xh
L
=

h=1
Nh
^ h )2
(s
N
nh
( )
= (1/10)2 (.14) + (5/10)2 (.12) + (3/10)2 (.20)
100
100
100
+ (1/10)2 (.18) = .000512
100
sxst =.0226
12