5629.0 - Inventories and Sales, Selected Industries, Australia, Sep 2001  
ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 03/12/2001   
   Page tools: Print Print Page Print all pages in this productPrint All

STANDARD ERRORS


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.


LEVEL ESTIMATES

To illustrate, let us say that the published level estimate for total inventories is $77,000m and the calculated standard error in this case is $965m. The standard error is then used to interpret the level estimate of $77,000m.

For instance, the standard error of $965m indicates that:

  • There are approximately two chances in three that the real value falls within the range $76,035m to $77,965m ($77,000m ± $965m).
  • There are approximately nineteen chances in twenty that the real value falls within the ranges $75,070m and $78,930m ($77,000m ± $1,930m).

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

The following tables show the standard errors for national quarterly level estimates based upon the data in the current quarter.


Inventories
$m
Mining
72
Manufacturing
414
Wholesale trade
897
Retail trade
737
Other
64
Total selected industries
1,237
Income from sales of goods and services
$m
Manufacturing
818
Wholesale trade
2,036
Motor vehicle retailing services
740
Accommodation
195
Transport and storage
545
Communication services
158
Property and business services
1,051
Cultural and recreation services
259
Personal services
208
Total selected industries
2,633

MOVEMENT ESTIMATES

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 inventories is $77,000m, and the next quarter the published level estimate is $79,000m. In this example the calculated standard error for the movement estimate is $754m. The standard error is then used to interpret the published movement estimate of +$2,000m.

For instance, the standard error of $754m indicates that:
  • There are approximately two chances in three that the real movement over the two quarter period falls within the range $1,246m to $2,754m ($2,000m ± $754m).
  • There are approximately nineteen chances in twenty that the real movement falls within the range $492m to $3,508m ($2,000m ± $1,508m).

The following tables shows the standard errors for national quarterly movement estimates based upon the data in the current quarter.


Inventories
$m
Mining
105
Manufacturing
367
Wholesale trade
695
Retail trade
389
Other
61
Total selected industries
878
Income from sales of goods and services
$m
Manufacturing
681
Wholesale trade
1,361
Motor vehicle retailing services
431
Accommodation
152
Transport and storage
302
Communication services
142
Property and business services
773
Cultural and recreation services
426
Personal services
119
Total selected industries
1,835