Ethnic counts on mortality and census data 2001-06: New Zealand census-mortality study update

Area of Science:

• Demographic studies
• Public health research
• Statistical analysis

Background:

• Accurate ethnicity data is crucial for understanding health disparities.
• Previous assessments (2001-2004) indicated minimal bias in ethnicity counts between census and mortality data.
• The 2001 census and subsequent mortality data linkage provides a valuable resource for validation.

Purpose of the Study:

• To update the assessment of discrepancies in ethnicity counts between census and mortality data.
• To compare ethnicity recording in the 2001 census with mortality data from 2004-2006.
• To evaluate the impact of different ethnicity definitions on count comparisons.

Main Methods:

• Anonymously and probabilistically linked 2001 census data with 5 years of mortality records (135,849 records).
• Compared ethnicity recording between the 2001 census and mortality data for 2001-2004 and 2004-2006.
• Analyzed discrepancies using both total and sole ethnicity definitions.

Main Results:

• Census and mortality counts showed reasonable agreement for total ethnicity in 2004-2006, similar to 2001-2004.
• Counts for Pacific and Asian ethnicities were up to a third lower in mortality data at younger ages.
• Sole ethnicity counts were generally higher in mortality data than census data, especially for Maori ethnicity.

Conclusions:

• Little bias exists in ethnic group counts between census and mortality data when using the total ethnicity definition.
• Calculations of mortality rates by ethnicity using unlinked data and total ethnicity definition should be unbiased.
• Results support the continued use of the census definition of ethnicity across all health datasets.