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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 males aged 90+ in each year 1976–1996.
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pone.0123692.g006: Weighted Mean Absolute Percentage Errors for Australian males aged 90+ in each year 1976–1996.

Mentions: The pattern for males is similar, as can be seen in Fig 6, which shows a comparison of WMAPEs in each year from 1976 to 1996 for ages 90+. Results for SR(5,3,90+) and SR(5,3,85+) are very similar in each year to those for SR(5,5,90+) and SR(5,5,85+) and are not shown. Errors for DG variants exceeded 5% in most years and were very volatile over the period. The ABS ERPs and SR variants constrained to ERPs produced errors consistently below 5% in the years 1976 to 1982, but gradually deteriorated to 1990, producing errors of between 5% and 10%. From 1991 onwards, errors from ABS ERPs and variants constrained to 90+ ERPs consistently increased from around 5% to over 12% and were the least accurate of all the methods considered. From 1984 to 1991 the unconstrained SR variants produced the most accurate estimates, and from 1991 onwards SR(5,3,85+) and SR(5,5,85+) produced the lowest errors overall.


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 males aged 90+ in each year 1976–1996.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0123692.g006: Weighted Mean Absolute Percentage Errors for Australian males aged 90+ in each year 1976–1996.
Mentions: The pattern for males is similar, as can be seen in Fig 6, which shows a comparison of WMAPEs in each year from 1976 to 1996 for ages 90+. Results for SR(5,3,90+) and SR(5,3,85+) are very similar in each year to those for SR(5,5,90+) and SR(5,5,85+) and are not shown. Errors for DG variants exceeded 5% in most years and were very volatile over the period. The ABS ERPs and SR variants constrained to ERPs produced errors consistently below 5% in the years 1976 to 1982, but gradually deteriorated to 1990, producing errors of between 5% and 10%. From 1991 onwards, errors from ABS ERPs and variants constrained to 90+ ERPs consistently increased from around 5% to over 12% and were the least accurate of all the methods considered. From 1984 to 1991 the unconstrained SR variants produced the most accurate estimates, and from 1991 onwards SR(5,3,85+) and SR(5,5,85+) produced the lowest errors overall.

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