8731.0 - Building Approvals, Australia, Apr 2002  
ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 03/06/2002   
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  • What If

EFFECT OF NEW SEASONALLY ADJUSTED ESTIMATES ON TREND ESTIMATES

Readers should exercise care when interpreting trend estimates. The last six trend estimates, in particular, are likely to be revised when new seasonally adjusted estimates become available.


TREND REVISIONS

Generally, the greater the volatility of the original series, the larger the size of the revisions to trend estimates. Analysis of the building approval original series has shown that they can be revised substantially. As a result, some months can elapse before turning points in the trend series are reliably identified.

The graphs and tables which follow present the effect of two possible scenarios on the previous trend estimates: that the May seasonally adjusted estimate is higher than the April estimate by 3% for the number of private sector houses approved and 11% for other dwelling units approved; and that the May seasonally adjusted estimate is lower than the April estimate by 3% for the number of private sector houses approved and 11% for other dwelling units approved. These percentages were chosen because they represent the average absolute monthly percentage change for these series over the last ten years.


PRIVATE SECTOR HOUSES APPROVED
WHAT IF NEXT MONTH’S SEASONALLY ADJUSTED ESTIMATE:
GRAPH - PRIVATE SECTOR HOUSES APPROVED
1
2
TREND AS PUBLISHED
rises by 3% on Apr 2002
falls by 3% on
Apr 2002
no.
% change
no.
% change
no.
% change
December 2001
10,002
-1.7
10,001
-1.7
10,025
-1.6
January 2002
9,847
-1.5
9,843
-1.6
9,855
-1.7
February 2002
9,718
-1.3
9,738
-1.1
9,706
-1.5
March 2002
9,607
-1.1
9,655
-0.9
9,551
-1.6
April 2002
9,494
-1.2
9,592
-0.6
9,397
-1.6
May 2002
n.y.a.
n.y.a.
9,551
-0.4
9,256
-1.5

WHAT IF NEXT MONTH’S SEASONALLY ADJUSTED ESTIMATE:
OTHER DWELLINGS
GRAPH - OTHER DWELLINGS
1
2
TREND AS PUBLISHED
rises by 11% on Apr 2002
falls by 11% on Apr 2002
no.
% change
no.
% change
no.
% change
December 2001
3,685
-2.6
3,625
-3.4
3,670
-2.8
January 2002
3,728
1.2
3,698
2.0
3,721
1.4
February 2002
3,928
5.4
4,004
8.3
3,945
6.0
March 2002
4,219
7.4
4,485
12.0
4,290
8.7
April 2002
4,585
8.7
5,023
12.0
4,656
8.5
May 2002
n.y.a.
n.y.a.
5,577
11.0
5,022
7.9