Responsibility for Excess Mortality Analysis in New Zealand
SPENCER JONES made this Official Information request to Ministry of Health
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From: SPENCER JONES
Tēnā koutou,
Pursuant to the Official Information Act 1982, I request the following information regarding the analysis of excess mortality in New Zealand.
1. Please identify which agency or agencies (if any) are responsible for:
• Analysing excess mortality (observed vs expected deaths), or
• Commissioning or overseeing such analyses at a national level.
2. Please advise whether the Ministry of Health or Health NZ – Te Whatu Ora:
• Has produced, commissioned, received, or relied upon any excess-mortality analyses since 2015 (whether published or unpublished).
3. If no such analyses are held, please confirm:
• Whether excess mortality analysis is considered outside the scope of all New Zealand public health agencies, and
• Whether the Ministry relies solely on external or international bodies for such analysis.
4. Please provide any documents, briefings, or internal guidance that describe:
• How mortality data is interpreted for population-level risk assessment in the absence of excess-mortality modelling.
If no documents exist for any part of this request, please confirm this explicitly under section 18(e).
This request is made in the public interest to clarify analytical accountability rather than to challenge any individual dataset.
Kind regards,
Spencer Jones
From: OIA Requests
Kia ora Spencer,
Thank you for your request under the Official Information Act 1982 (the
Act), received by the Ministry of Health on 17 December 2025. You
requested:
"1. Please identify which agency or agencies (if any) are
responsible for:
• Analysing excess mortality (observed vs expected deaths),
or
• Commissioning or overseeing such analyses at a national
level.
2. Please advise whether the Ministry of Health or Health NZ
– Te Whatu Ora:
• Has produced, commissioned, received, or relied upon any
excess-mortality analyses since 2015 (whether published or unpublished).
3. If no such analyses are held, please confirm:
• Whether excess mortality analysis is considered outside
the scope of all New Zealand public health agencies, and
• Whether the Ministry relies solely on external or
international bodies for such analysis.
4. Please provide any documents, briefings, or internal
guidance that describe:
• How mortality data is interpreted for population-level
risk assessment in the absence of excess-mortality modelling."
The reference number for your request is H2025077117. As required under
the Act, the Ministry will endeavour to respond to your request no later
than 20 working days after the day your request was
received: [1]http://www.ombudsman.parliament.nz/.
Please be advised that due dates for requests received on 27 November 2025
onwards will take into account the summer holiday period (25 December 2025
to 15 January 2026). Please refer to this guide for an explanation of
the [2]statutory obligations under the Official Information Act 1982.
If you have any queries related to this request, please do not hesitate to
get in touch ([3][email address]).
Ngā mihi,
OIA Services Team
Ministry of Health | Manatū Hauora
M[4]inistry of Health information releases
------------------- Original Message -------------------
From: SPENCER JONES <[FOI #33301 email]>;
Received: Wed Dec 17 2025 11:20:05 GMT+1300 (New Zealand Daylight Time)
To: OIA Requests <[email address]>; OIA <[email address]>;
Subject: Official Information request - Responsibility for Excess
Mortality Analysis in New Zealand
Tēnā koutou,
Pursuant to the Official Information Act 1982, I request the following
information regarding the analysis of excess mortality in New Zealand.
1. Please identify which agency or agencies (if any) are
responsible for:
• Analysing excess mortality (observed vs expected deaths),
or
• Commissioning or overseeing such analyses at a national
level.
2. Please advise whether the Ministry of Health or Health NZ
– Te Whatu Ora:
• Has produced, commissioned, received, or relied upon any
excess-mortality analyses since 2015 (whether published or unpublished).
3. If no such analyses are held, please confirm:
• Whether excess mortality analysis is considered outside
the scope of all New Zealand public health agencies, and
• Whether the Ministry relies solely on external or
international bodies for such analysis.
4. Please provide any documents, briefings, or internal
guidance that describe:
• How mortality data is interpreted for population-level
risk assessment in the absence of excess-mortality modelling.
If no documents exist for any part of this request, please confirm this
explicitly under section 18(e).
This request is made in the public interest to clarify analytical
accountability rather than to challenge any individual dataset.
Kind regards,
Spencer Jones
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SPENCER JONES left an annotation ()
Annotation: Stats NZ OIA (Death statistics, 2015–2025) — what was answered, what was refused, what is still pending
Stats NZ has now issued its substantive response to the parts it retained, and earlier advised that parts 3, 4, and 7 were transferred to Health NZ – Te Whatu Ora because those parts were more closely connected to Health NZ’s functions. 
What Stats NZ did provide (practically)
For several items (e.g., annual deaths, age-standardised mortality rates, weekly deaths, and age-banded mortality counts), Stats NZ largely pointed to existing public sources (notably Infoshare and their births/deaths releases) and described how weekly registered deaths data is published (provisional, quarterly updates). 
This is a common approach: agencies will often treat “already publicly available” material as “provided” by directing requesters to the authoritative source, rather than exporting custom spreadsheets.
What Stats NZ refused (and why it matters)
Stats NZ refused the “excess mortality / expected deaths / baseline methodology” components under OIA s18(g) on the basis that the requested information is not held by Stats NZ (they state they do not measure excess deaths or maintain baseline methodologies/technical documentation for that purpose). 
This creates a clear “analytical gap” for the public:
• NZ has robust mortality counts and rates available,
• but official “expected vs observed / excess mortality” analysis is treated as outside Stats NZ’s holdings, and therefore must be sought from whichever agency (or cross-agency process) is responsible for that modelling—if it exists.
Is this OIA “complete” yet?
Not fully. The request is still live in substance because Health NZ has not yet delivered the transferred parts (3, 4, and 7). Stats NZ’s portion is complete; the overall request is not. 
What to watch next (without assuming bad faith)
When Health NZ replies, the key questions are:
1. Do they hold cause-of-death / ICD-coded outputs at the level requested (and what lags/limitations apply)?
2. Do they hold any internal analysis that compares mortality patterns pre-2020 vs post-2020, or is that also “not held”?
3. If they refuse as “not held”, do they identify who does hold the relevant modelling (or confirm it does not exist in NZ government)?
Comparable FYI requests (pattern-spotting, not allegations)
There are numerous FYI requests seeking mortality analytics, “excess deaths,” or “expected deaths” models. Results commonly include:
• directing to public data portals,
• “not held” refusals for modelling/baselines,
• partial transfers across agencies where holdings are split.
(If you want, I can maintain a rolling “related FYI requests” list under this annotation as new ones surface.)
International comparison (governance models)
In multiple jurisdictions, “excess deaths” is treated as a defined statistical product supported by published methods:
• US CDC / NCHS publishes excess-death estimates using modelling approaches (baseline/expected deaths with uncertainty), described in peer-reviewed/official methodology write-ups. 
• UK ONS routinely publishes weekly deaths and excess-death style comparisons with transparent statistical framing and documentation in its bulletins/method notes. 
The key governance distinction is: some systems treat excess-mortality as an owned, documented, routinely-published product (with defined methods and revision policy), while NZ’s response here suggests that, at least for Stats NZ, it is not treated as an internal “held” output in the way requesters often assume. 
Status: Stats NZ response received; Health NZ response pending (transferred parts).
Link to this