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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

Percentage Errors at ages 100+ for Australian females in each year 1976–1996.
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pone.0123692.g009: Percentage Errors at ages 100+ for Australian females in each year 1976–1996.

Mentions: Percentage Errors (PEs) in years 1976 to 1996 for ABS ERPs were compared with those from variants of the SR and SA methods in Figs 9 and 10 (females and males respectively). The graphs clearly show that ABS ERPs at ages 100+ exhibit more volatile error patterns compared to methods based on nearly-extinct cohort methods. For females PEs varied between extremes of -46% in 1984 and 26% in 1988, indicating underestimation in some years and overestimation in others. For males, PEs for ERPs varied between extremes of -21% and 94%, but generally they were overestimated.


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)

Percentage Errors at ages 100+ for Australian females in each year 1976–1996.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0123692.g009: Percentage Errors at ages 100+ for Australian females in each year 1976–1996.
Mentions: Percentage Errors (PEs) in years 1976 to 1996 for ABS ERPs were compared with those from variants of the SR and SA methods in Figs 9 and 10 (females and males respectively). The graphs clearly show that ABS ERPs at ages 100+ exhibit more volatile error patterns compared to methods based on nearly-extinct cohort methods. For females PEs varied between extremes of -46% in 1984 and 26% in 1988, indicating underestimation in some years and overestimation in others. For males, PEs for ERPs varied between extremes of -21% and 94%, but generally they were overestimated.

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