WHAT IF...? REVISIONS TO TREND ESTIMATES
EFFECT OF NEW SEASONALLY ADJUSTED ESTIMATES ON TREND ESTIMATES
TREND REVISIONS
Recent seasonally adjusted and trend estimates are likely to be revised when original estimates for subsequent months become available. The approximate effect of possible scenarios on trend estimates are presented below. 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 July seasonally adjusted estimate is higher than the June estimate by 2.4% for the number of private sector houses approved and 14.0% for private sector dwellings excluding houses approved; and that the July seasonally adjusted estimate is lower than the June estimate by 2.4% for the number of private sector houses approved and 14.0% for private sector dwellings excluding houses approved. These percentages represent the average absolute monthly percentage change for these series over the last ten years.
APPROVED PRIVATE SECTOR HOUSES
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| | | | WHAT IF NEXT MONTH'S SEASONALLY ADJUSTED ESTIMATE: |
| | Trend as published | (1) rises by 2.4% on Jun 2019 | (2) falls by 2.4% on Jun 2019 |
| | no. | % change | no. | % change | no. | % change |
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2019 | | | | | | |
| January | 9 107 | -1.6 | 9 099 | -1.7 | 9 107 | -1.6 |
| February | 8 946 | -1.8 | 8 932 | -1.8 | 8 946 | -1.8 |
| March | 8 797 | -1.7 | 8 790 | -1.6 | 8 797 | -1.7 |
| April | 8 674 | -1.4 | 8 693 | -1.1 | 8 675 | -1.4 |
| May | 8 579 | -1.1 | 8 636 | -0.7 | 8 574 | -1.2 |
| June | 8 514 | -0.8 | 8 610 | -0.3 | 8 495 | -0.9 |
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APPROVED PRIVATE SECTOR DWELLINGS EXCLUDING HOUSES
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| | | | WHAT IF NEXT MONTH'S SEASONALLY ADJUSTED ESTIMATE: |
| | Trend as published | (1) rises by 14.0% on Jun 2019 | (2) falls by 14.0% on Jun 2019 |
| | no. | % change | no. | % change | no. | % change |
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2019 | | | | | | |
| January | 5 943 | 0.8 | 5 927 | 0.5 | 5 956 | 1.0 |
| February | 6 018 | 1.3 | 5 998 | 1.2 | 6 049 | 1.6 |
| March | 6 061 | 0.7 | 6 050 | 0.9 | 6 076 | 0.4 |
| April | 6 007 | -0.9 | 6 026 | -0.4 | 5 959 | -1.9 |
| May | 5 884 | -2.1 | 5 912 | -1.9 | 5 691 | -4.5 |
| June | 5 736 | -2.5 | 5 796 | -2.0 | 5 379 | -5.5 |
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