1
SIMPLERANDOMSAMPLE
2
SYSTEMATICSAMPLE
3
CLUSTERSAMPLE
4
SECONDARYDATA
5
PROBABILITY
6
STRATIFIED
7
STATISTICS
8
TECHNIQUE
9
ACCURATE
10
UNBIAS
11
CENSUS
12
ERROR
13
BIAS
14
POLL
O
N
A
X
S
T
R
A
T
I
F
I
E
D
E
A
H
Y
Q
N
E
T
R
E
B
M
E
A
C
C
U
R
A
T
E
Y
N
A
Q
A
R
T
S
C
N
C
L
U
S
T
E
R
S
A
M
P
L
E
Z
T
O
U
C
W
L
U
P
K
N
E
R
R
O
R
V
U
Q
P
I
A
Y
R
I
F
U
N
M
Y
U
M
O
Y
V
S
I
O
C
A
E
D
S
E
T
R
A
Z
A
D
U
I
A
O
K
Y
H
X
G
E
U
Y
A
I
S
T
L
V
S
Q
G
U
O
U
E
S
X
S
P
M
E
R
I
Z
I
A
Z
C
M
A
K
Y
P
L
J
T
I
B
M
O
O
A
B
A
T
K
F
E
O
A
U
O
R
Z
I
E
A
E
O
Y
E
D
N
U
A
G
I
O
D
E
U
Y
O
X
O
M
E
I
K
Y
V
N
U
Y
T
N
J
T
N
L
E
U
B
U
Z
A
U
I
D
A
S
O
P
Z
S
Z
M
T
A
S
P
L
A
A
C
T
A
Y
I
E
A
C
Z
O
B
B
Q
E
R
A
P
A
B
C
F
I
G
G
A
E
N
E
I
E
U
W
O
C
E
I
R
I
I
E
P
C
A
U
A
A
A
S
B
H
I
X
Q
H
L
B
A
J
L
N
O
S
U
V
E
C
K
T
I
O
U
N
C
N
P
T
R
Z
I
S
J
A
S
B
P
V
L
P
E
U
E
C
E
I
M
A
Y
I
T
U
A
M
O
J
O
P
Z
T
R
A
R
E
W
Q
I
U
T
K
Y
S
U
P
Q
U
A
G
I
X
V
B
E
E
S
U
S
P
O
L
L
E
X
L
L
U
B
B
M
O
E
W
D
U
X
E
O
D
W
A
A
S
G
E
U
R
N
C
O
U