APPENDIX 3 ALTERNATIVE APPROACHES TO ADJUST DEATHS


INTRODUCTION

In Experimental Life Tables for Aboriginal and Torres Strait Islander Australians, 2005-2007 (cat. no. 3302.0.55.003) the ABS presented six alternative approaches for adjusting deaths data as an input to compilation of life tables. While not the best method each of these approaches does provide useful insights into the official method and where it adds particular value. Four methods have been included for 2010-2012.


ALTERNATIVE APPROACHES TO ADJUST DEATHS

The four alternative approaches for which illustrative estimates were produced were:

1. using deaths identified as Aboriginal and Torres Strait Islander in death registrations without any adjustment;

2. using deaths identified as Aboriginal and Torres Strait Islander in either the Census or death registrations in the CDE linked data only;

3. using deaths identified as Aboriginal and Torres Strait Islander in either the Census or death registrations in the CDE linked and unlinked data; and

4. using Aboriginal and Torres Strait Islander identification based on the 2011 Census.

The first approach shows what life expectancy would have been if no adjustment was made for the underidentification of Indigenous status in deaths registration data.

The second and third approaches are provided here as approaches that were explored by the ABS for the previous 2005-2007 estimates but were considered to be unsuitable for estimating Aboriginal and Torres Strait Islander mortality. The main reason for this is that the identification of Indigenous status in the numerator (deaths) and the denominator (population estimates) are not consistent with each other, thus introducing bias to life expectancy estimates.

The fourth approach was also explored by the ABS, but the resultant life expectancy at birth estimates were considerably higher than the other estimates and not considered to be plausible.

A brief discussion of each of the different approaches and the results obtained are presented below.


1. Deaths identified as Aboriginal and Torres Strait Islander in death registrations without any adjustment

This method produces life expectancy estimates based on no adjustment made to the number of Aboriginal and Torres Strait Islander deaths to account for underidentification. This shows that no adjustment to the number of deaths leads to higher life expectancy for New South Wales, Queensland and Australia and lower life expectancy for Western Australia and the Northern Territory.

A3.1 ABORIGINAL AND TORRES STRAIT ISLANDER LIFE EXPECTANCY AT BIRTH, based on unadjusted death registrations - 2010-2012
	Males	Females
State/territory	years	years
NSW	74.6	77.7
Qld	71.4	76.6
WA	66.9	71.8
NT	62.9	68.0
Aust.(a)	71.5	75.7
(a) Includes all states and territories.

2. Deaths identified as Aboriginal and Torres Strait Islander in either Census or death registrations in the CDE linked data only

For the previous 2005-2007 estimates, ABS explored an option to derive identification rates for Aboriginal and Torres Strait Islander deaths and life expectancy estimates using the CDE linked data only.

This approach uses a concept of Indigenous status which is different from that used for the denominator for death rates; that is, population estimates where Indigenous status is as reported in PES only but not augmented by other sources of information. In calculating life expectancy estimates, it is important to ensure that the classification of records as Aboriginal and Torres Strait Islander occurs in a consistent manner in the numerator (deaths) and the denominator (population estimates) as different population scopes feed directly into bias in death rates.

A3.2 CDE LINKED DATA(a), Identification rates and life expectancy estimates based on Aboriginal and Torres Strait Islander deaths - 2010-2012
					LIFE EXPECTANCY AT BIRTH
	Aboriginal and Torres Strait Islander deaths in death registrations	Additional Aboriginal and Torres Strait Islander deaths identified in Census only	Total Aboriginal and Torres Strait Islander deaths by deaths registrations or Census	Aboriginal and Torres Strait Islander deaths identification rate(b)	Males	Females
State/territory	no.	no.	no.	no.	years	years
NSW	604	268	872	0.69	70.3	74.1
Qld	520	130	650	0.80	68.6	74.2
WA	276	40	316	0.87	65.0	70.1
NT	262	4	266	0.98	62.6	67.8
Aust.(c)	1 884	606	2 490	0.76	67.8	72.6
(a) Deaths identified in either Census or registration in the CDE linked data.
(b) Ratio of Aboriginal and Torres Strait Islander deaths identified in death registrations to the total Aboriginal and Torres Strait Islander deaths identified in either registration and Census.
(c) Includes all states and territories.

3. Deaths identified as Aboriginal and Torres Strait Islander in either Census or death registrations in the CDE linked and unlinked data

This approach, like the previous approach, is based on Aboriginal and Torres Strait Islander deaths identified in either the Census or death registrations, but uses the Aboriginal and Torres Strait Islander deaths identified in the CDE linked file plus those Aboriginal and Torres Strait Islander deaths which were unable to be linked to a Census record.

A3.3 CDE LINKED AND UNLINKED DATA(a), Identification rates and life expectancy estimates based on Aboriginal and Torres Strait Islander deaths - 2010-2012
				LIFE EXPECTANCY AT BIRTH ESTIMATES
	Aboriginal and Torres Strait Islander deaths from death registrations prior to linkage	Aboriginal and Torres Strait Islander deaths after linkage	Aboriginal and Torres Strait Islander deaths identification rate(b)	Males	Females
State/territory	no.	no.	no.	years	years
NSW	718	985	0.73	71.0	74.6
Qld	608	739	0.82	69.0	74.5
WA	379	419	0.90	65.5	70.6
NT	360	364	0.99	62.7	67.8
Aust.(c)	2 345	2 951	0.79	68.4	73.1
(a) Deaths identified in either Census or registration in the CDE linked and unlinked data.
(b) Ratio of Aboriginal and Torres Strait Islander deaths prior to linkage to Aboriginal and Torres Strait Islander deaths after linkage.
(c) Includes all states and territories.

Like the previous approach, this approach also produces life expectancy estimates which are biased as the identification of Indigenous status in the numerator and the denominator are inconsistent.


4. Direct method using identification based on the 2011 Census

The CDE linked dataset can be used to derive direct estimates of mortality of the Aboriginal and Torres Strait Islander population counted in the 2011 Census. The method of estimation involves a three stage process.

Firstly, people who identified themselves as Aboriginal and Torres Strait Islander in the 2011 Census were selected from the Census.

Secondly, only those death records for which Indigenous status was reported as Aboriginal and Torres Strait Islander in the Census were taken from the linked file.

Thirdly, age-specific death rates were calculated by dividing the Aboriginal and Torres Strait Islander deaths by the Aboriginal and Torres Strait Islander Census counts. These rates were then used to derive Aboriginal and Torres Strait Islander life tables. No adjustments were made to the death rates to account for potential undercoverage of deaths, hence the method is referred to as 'direct'.

This approach was intended to make Aboriginal and Torres Strait Islander counts for deaths and for the population at risk (that is, Aboriginal and Torres Strait Islander usual residents of Australians) consistent. However, this is not the case. Due to undercount in Census a proportion of death records could not be linked, as there was no corresponding Census record to link with. Such people are removed from the counts of deaths and from the counts of the population at risk. However, people whose information from death registrations or Census is not accurate enough to make a link are not included in the death counts, but it is not possible to remove from the Census count the corresponding count of people with unlinkable information in Census or what would have been unlinkable information from death registrations, had they died.