Producer Price Index Manual: Theory and Practice ... - METAC

Producer Price Index Manual
Table 5.1. Step 1 for Establishment Sample Selection
Table 5.2. Step 2 for Establishment Sample Selection
Establishment
Identifier
Size (value
of production
in millions)
Cumulative
Size
Cumulative
Percent
E 200 200 34
C 100 300 52
D 80 380 66
B 60 440 76
G 50 490 84
F 40 530 91
H 30 560 97
A 20 580 100
Establishment
Identifier
Size (value of
production in
millions)
Cumulative
size
C 100 100
D 80 180
B 60 240
G 50 290
F 40 330
H 30 360
A 20 380
The sampling interval is calculated:
cummulative grand total
Sampling interval =
number of sample units
580
= = 145.
4
5.68 All establishments with production values
greater than the sampling interval (145) have 100
percent probability of selection and are known as
“certainty units” (Establishment E). These selected
units are removed from the frame, we recalculate
the cumulative size, and a new sampling interval is
calculated using the reduced frame and the remaining
number of sample units to be allocated (as
shown in Table 5.2).
cummulative grand total
Sampling interval =
sample allocation
380
= = 127.
3
5.69 If there are new certainty units in the reduced
sample, these are removed (not in this case)
and the process is repeated until a sampling interval
is calculated for which there are no certainty units.
This sampling interval is used for systematic sampling.
The remaining sample is sorted (largest to
Table 5.3. Step 3 for Establishment Sample Selection
Establishment
Identifier
Size (value of
production in millions)
Cumulative
Size
C 100 100
D 80 180
B 60 240
G 50 290
F 40 330
H 30 360
A 20 380
smallest as shown in Table 5.3), a random number
between 0 and 1 is generated, and the sampling interval
is multiplied by this random number to give
the starting point for the sampling pattern.
Random number = 0.34128
Sarting point: 0.34128 x 127 = 43
Sampling pattern:
43 (43 + 127) (43 + 127 + 127)
43 170 297
Thus Establishments C, D, and F are selected, giving
a total sample of C, D, E, and F.
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