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An evaluation of nearly-extinct cohort methods for estimating the very elderly populations of australia and new zealand.

Terblanche W, Wilson T - PLoS ONE (2015)

Bottom Line: However, it is recognised that estimates derived from census counts are often unreliable.Official estimates in Australia proved reasonably accurate for ages 90+ but at 100+ they varied significantly in accuracy from year to year.Estimates produced by Statistics New Zealand in aggregate for ages 90+ proved very accurate.

View Article: PubMed Central - PubMed

Affiliation: Queensland Centre for Population Research, School of Geography, Planning and Environmental Management, The University of Queensland, Brisbane, Queensland, Australia.

ABSTRACT
The rapid growth of very elderly populations requires accurate population estimates up to the highest ages. However, it is recognised that estimates derived from census counts are often unreliable. Methods that make use of death data have not previously been evaluated for Australia and New Zealand. The aim was to evaluate a number of nearly-extinct cohort methods for producing very elderly population estimates by age and sex for Australia and New Zealand. The accuracy of official estimates was also assessed. Variants of three nearly-extinct cohort methods, the Survivor Ratio method, the Das Gupta method and a new method explicitly allowing for falling mortality over time, were evaluated by retrospective application over the period 1976-1996. Estimates by sex and single years of age were compared against numbers derived from the extinct cohort method. Errors were measured by the Weighted Mean Absolute Percentage Error. It is confirmed that for Australian females the Survivor Ratio method constrained to official estimates for ages 90+ performed well. However, for Australian males and both sexes in New Zealand, more accurate estimates were obtained by constraining the Survivor Ratio method to official estimates for ages 85+. Official estimates in Australia proved reasonably accurate for ages 90+ but at 100+ they varied significantly in accuracy from year to year. Estimates produced by Statistics New Zealand in aggregate for ages 90+ proved very accurate. We recommend the use of the Survivor Ratio method constrained to official estimates for ages 85+ to create very elderly population estimates for Australia and New Zealand.

No MeSH data available.


Related in: MedlinePlus

Weighted Mean Absolute Percentage Errors for Australian females aged 100+ in each year 1976–1996.Note. ABS ERPs are not included because only an aggregate ERP is available for ages 100+, which means WMAPE cannot be determined.
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pone.0123692.g007: Weighted Mean Absolute Percentage Errors for Australian females aged 100+ in each year 1976–1996.Note. ABS ERPs are not included because only an aggregate ERP is available for ages 100+, which means WMAPE cannot be determined.

Mentions: Fig 7 compares the WMAPEs at ages 100+ for Australian females in each year from 1976 to 1996 for the same methods as shown in Fig 5. On average over the study period, the SR method with survivor ratios measured over 5-year age ranges resulted in the lowest errors, with only marginal differences between variants which applied different ERP constraints. While all methods display volatile errors from 1976 to 1984, the SR(5,5,NC) method produced the lowest errors after 1984, and was one of the best three methods in 9 of the 12 years from 1985 to 1996.


An evaluation of nearly-extinct cohort methods for estimating the very elderly populations of australia and new zealand.

Terblanche W, Wilson T - PLoS ONE (2015)

Weighted Mean Absolute Percentage Errors for Australian females aged 100+ in each year 1976–1996.Note. ABS ERPs are not included because only an aggregate ERP is available for ages 100+, which means WMAPE cannot be determined.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4388836&req=5

pone.0123692.g007: Weighted Mean Absolute Percentage Errors for Australian females aged 100+ in each year 1976–1996.Note. ABS ERPs are not included because only an aggregate ERP is available for ages 100+, which means WMAPE cannot be determined.
Mentions: Fig 7 compares the WMAPEs at ages 100+ for Australian females in each year from 1976 to 1996 for the same methods as shown in Fig 5. On average over the study period, the SR method with survivor ratios measured over 5-year age ranges resulted in the lowest errors, with only marginal differences between variants which applied different ERP constraints. While all methods display volatile errors from 1976 to 1984, the SR(5,5,NC) method produced the lowest errors after 1984, and was one of the best three methods in 9 of the 12 years from 1985 to 1996.

Bottom Line: However, it is recognised that estimates derived from census counts are often unreliable.Official estimates in Australia proved reasonably accurate for ages 90+ but at 100+ they varied significantly in accuracy from year to year.Estimates produced by Statistics New Zealand in aggregate for ages 90+ proved very accurate.

View Article: PubMed Central - PubMed

Affiliation: Queensland Centre for Population Research, School of Geography, Planning and Environmental Management, The University of Queensland, Brisbane, Queensland, Australia.

ABSTRACT
The rapid growth of very elderly populations requires accurate population estimates up to the highest ages. However, it is recognised that estimates derived from census counts are often unreliable. Methods that make use of death data have not previously been evaluated for Australia and New Zealand. The aim was to evaluate a number of nearly-extinct cohort methods for producing very elderly population estimates by age and sex for Australia and New Zealand. The accuracy of official estimates was also assessed. Variants of three nearly-extinct cohort methods, the Survivor Ratio method, the Das Gupta method and a new method explicitly allowing for falling mortality over time, were evaluated by retrospective application over the period 1976-1996. Estimates by sex and single years of age were compared against numbers derived from the extinct cohort method. Errors were measured by the Weighted Mean Absolute Percentage Error. It is confirmed that for Australian females the Survivor Ratio method constrained to official estimates for ages 90+ performed well. However, for Australian males and both sexes in New Zealand, more accurate estimates were obtained by constraining the Survivor Ratio method to official estimates for ages 85+. Official estimates in Australia proved reasonably accurate for ages 90+ but at 100+ they varied significantly in accuracy from year to year. Estimates produced by Statistics New Zealand in aggregate for ages 90+ proved very accurate. We recommend the use of the Survivor Ratio method constrained to official estimates for ages 85+ to create very elderly population estimates for Australia and New Zealand.

No MeSH data available.


Related in: MedlinePlus