5629.0 - Inventories and Sales, Selected Industries, Australia, Sep 2001
Latest ISSUE Released at 11:30 AM (CANBERRA TIME) 03/12/2001
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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