5625.0 - Private New Capital Expenditure and Expected Expenditure, Australia, Jun 2005  
ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 01/09/2005   
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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

To illustrate, let us say that the published level estimate for total capital expenditure is $10,500m and the calculated standard error in this case is $173m. The standard error is then used to interpret the level estimate of $10,500m. For instance, the standard error of $173m indicates that:

  • There are approximately two chances in three that the real value falls within the range $10,327m to $10,673m ($10,500m ± $173m)
  • There are approximately 19 chances in 20 that the real value falls within the ranges $10,154m and $10,846m ($10,500m ± $346m)

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 quarterly level estimates. These standard errors are based on a smoothed average of capital expenditure estimates.

Buildings and structures
Equipment, plant and machinery
Total
$m
$m
$m
Mining
11
16
36
Manufacturing
16
51
62
Construction
7
35
40
Wholesale trade
5
57
65
Retail trade
7
22
34
Transport and storage
10
40
45
Finance and insurance
3
29
31
Property and business services
52
62
84
Other services
69
36
89
Total
90
124
173
New South Wales
17
77
92
Victoria
73
71
108
Queensland
10
35
44
South Australia
2
13
27
Western Australia
5
25
32
Tasmania
1
8
8
Northern Territory
na
na
2
Australian Capital Territory
na
na
6
Australia
90
124
173
na not available



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 $10,500m, and the next quarter the published level estimate is $11,100m. In this example the calculated standard error for the movement estimate is $221m. The standard error is then used to interpret the published movement estimate of +$600m.


For instance, the standard error of $221m indicates that:

  • There are approximately two chances in three that the real movement over the two quarter period falls within the range $379m to $821m ($600m ±$221m)
  • There are approximately nineteen chances in twenty that the real movement falls within the range $158m to $1,042m ($600m ± $442m)

The following table shows the standard errors for national quarterly movement estimates. These standard errors are based on a smoothed average of capital expenditure estimates.


Buildings and structures
Equipment, plant and machinery
Total
$m
$m
$m
Mining
15
23
49
Manufacturing
22
64
78
Construction
10
48
55
Wholesale trade
7
51
66
Retail trade
11
25
45
Transport and storage
12
49
53
Finance insurance
5
40
32
Property and business services
74
84
114
Other services
98
46
119
Total
127
153
221
New South Wales
26
99
103
Victoria
26
114
117
Queensland
63
75
100
South Australia
10
84
84
Western Australia
24
87
91
Tasmania
5
21
21
Northern Territory
na
na
33
Australian Capital Territory
na
na
67
Australia
127
153
221
na not available