5625.0 - Private New Capital Expenditure and Expected Expenditure, Australia, Sep 2011 Quality Declaration 
ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 30/11/2011   
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APPENDIX SAMPLING ERRORS


LEVEL ESTIMATES


INTRODUCTION

The estimates in this publication are based on a sample drawn from units in the surveyed population. Because the entire population is not surveyed, the published estimates are subject to sampling error. The most common way of quantifying such sampling error is to calculate the standard error for the published estimate or statistic.


EXAMPLE OF USE

The following example illustrates how to use the standard error to interpret a level estimate.

Let us say that the published level estimate for total capital expenditure is $34,807m and the calculated standard error in this case is $634m. The standard error is then used to interpret the level estimate of $34,807m.

For instance, the standard error of $634m indicates that:

  • There are approximately two chances in three that the real value falls within the range $34,173m to $35,441m (34,807m ± $634m).
  • There are approximately 19 chances in 20 that the real value falls within the range $33,539m to $36,075m (34,807m ± $1,268m).

The real value in this case is the result we would obtain if we could enumerate the total population.

The following table shows the standard errors for September Quarter 2011 estimates.

Buildings and Structures
Equipment, Plant and Machinery
Total
$m
$m
$m
Mining
314
63
319
Manufacturing
46
114
140
Electricity, Gas, Water and Waste Services
4
17
20
Construction
14
108
111
Wholesale Trade
51
64
86
Retail Trade
42
63
72
Transport, Postal and Warehousing
52
133
147
Information Media and Telecommunications
-
24
24
Financial and Insurance Services
11
30
35
Rental, Hiring and Real Estate Services
312
126
335
Professional, Scientific and Technical Services
73
63
109
Other Selected Services
129
208
243
Total
476
381
634
New South Wales
230
225
353
Victoria
246
140
295
Queensland
51
137
153
South Australia
23
121
121
Western Australia
337
126
353
Tasmania
5
40
40
Northern Territory
3
11
11
Australian Capital Territory
-
14
14
Australia
476
381
634
- nil or rounded to zero (including null cells)



MOVEMENT ESTIMATES


EXAMPLE OF USE

The following example illustrates how to use the standard error to interpret a movement estimate.

Let us say that one quarter the published level estimate for total capital expenditure is $34,383m and the next quarter the published level estimate is $34,807m.

In this example the calculated standard error for the movement estimate is $608m. The standard error is then used to interpret the published movement estimate of $424m.

For instance, the standard error of $608m indicates that:
  • There are approximately two chances in three that the real movement over the two quarter period falls within the range -$184m to $1,032m ($424m ± $608m).
  • There are approximately nineteen chances in twenty that the real movement falls within the range -$792m to $1,640m ($424m ± $1,216m).

The following table shows the standard errors for September Quarter 2011 movement estimates.

Buildings and Structures
Equipment, Plant and Machinery
Total
$m
$m
$m
Mining
102
356
269
Manufacturing
24
87
94
Electricity, Gas, Water and Waste Services
9
6
12
Construction
14
197
196
Wholesale Trade
54
76
99
Retail Trade
41
92
104
Transport, Postal and Warehousing
50
189
198
Information Media and Telecommunications
2
21
20
Financial and Insurance Services
11
96
96
Rental, Hiring and Real Estate Services
463
147
470
Professional, Scientific and Technical Services
77
104
131
Other Selected Services
124
213
273
Total
473
544
608
New South Wales
163
247
307
Victoria
258
177
298
Queensland
364
229
443
South Australia
27
89
92
Western Australia
134
353
304
Tasmania
7
39
41
Northern Territory
61
13
61
Australian Capital Territory
2
13
13
Australia
473
544
608