Panel:

• Ana Basiri (MARP representative – University of Glasgow) (Chair)
• Jon Forster (University of Warwick)
• Arkadiusz Wisniowski (University of Manchester)
• Fred Piel (Imperial College London)
• George Ploubidis (University College London)

ONS representatives:

• Nick Taylor (ONS)
• Dominic Webber (ONS)
• Joe Southam- Gisby (ONS)
• Greg Payne (ONS)
• Emma Ward (ONS)
• Sophie Gilbert – Johns (ONS)
• Andrew Taylor (ONS)
• Pratibha Vellanki (ONS)
• Salah Merad (ONS)
• Claire Hill (ONS)
• Paula Moore (ONS)

Welcome address and status of prior actions

The Chair welcomed the panel and proceeded to address the currently open actions.

Open actions:

Action DPMSG009 – Update to membership list: Consider adding international experts in Bayesian demography to the membership list.

Update on action: ONS explained that, following discussions at the October panel, it reviewed the membership list to consider bringing in additional international experts in Bayesian modelling, like the approach taken in the Migration sub‑panel. However, recent internal reviews of admin‑based population estimates have concluded that ONS will no longer adopt Admin-Based Population Estimates (ABPEs) as official population estimates. With work on the Dynamic Population Model (DPM) being paused, the context for expanding the expert list has changed. ONS will continue reviewing the membership list, but the original action is no longer relevant in its current form.

This action will be closed, and a new one may be opened in the future with updated reasoning if needed.

Action DPMSG010: Aggregate Uncertainty – War Room Brainstorming session
Organise a ‘war-room’ brainstorming session for aggregate uncertainty challenge.

Update on action: Given that work on the DPM has been paused, this action will be closed. A session can be arranged in future if needed.

Please note that Actions 004–008 will be closed following internal reviews confirming that ONS will not adopt Admin‑Based Population Estimates (ABPEs) as official population estimates, as announced in our recent quarterly update in March 2026. This also reflects the pause in work on the Dynamic Population Model (DPM) and the revised remit of the group. 

Quarterly update on population and migration statistics – Office for National Statistics 

Action DPMSG004: ONS to provide an update on the December Ops group meeting on international migration coherence and discuss options for managing incoherence in more detail at the next sub-MARP meeting.

Action:  DPMSG005: ONS to produce and share sensitivity analysis testing the impact of LTIM method changes on differences between international migration DPM inputs and outputs.

Action DPMSG006: Share the full 68-page report with panel members to improve transparency and understanding.

Action DPMSG07: Upload presentation slides to Confluence in PDF format to enable easier viewing and commenting.

Action DPMSG008: Members to review and comment on the direction of work before the next Sub-MARP meeting in January. Any outstanding points not addressed in comments will be discussed at the meeting.

ONS Retrospective: Overview and changes to the way ONS uses the panel – presented by  Dom Webber  ONS 

ONS introduced the new main point of contact and coordinator for the DPM sub-MARP group. 

The group held a retrospective to review its first year of operation. Feedback gathered through an external survey and an internal retrospective highlighted several themes for improving the way that ONS and the panel work together.  

The panel thanked ONS for the work undertaken and welcomed the retrospective and its clear recommendations for strengthening the subgroup’s effectiveness, noting the importance of continued feedback gathering across MARP subgroups once other reviews are complete.  

Overview of Population Estimates review – presented by Claire Hill ONS 

At the end of 2025, ONS conducted a review into population estimates, and have since determined that they are no longer adopting Admin-Based Population Estimates (ABPEs) as official statistics.

ONS committed to shifting towards a continuous improvement approach, rather than a major “big‑bang” methodological change from cohort‑component estimates to DPM. 

Resources are being rebalanced away from DPM development toward strengthening underlying population change components, particularly internal and international migration data. 

At the same time, teams will also explore alternative methods to measure the population (described further as a separate agenda item).  

Several DPM-related pieces of work remain ongoing (e.g., the technical manual), but overall DPM research will slow while focus shifts to improving inputs and exploring alternatives. 

The panel discussed the decision to slow down research on the DPM and explored what this means for its future. The group emphasised that the Research Maturity Framework now supports a more evidence‑driven process, allowing the research to speak for itself. The DPM was described as a potentially valuable approach but one that carries significant complexity, communication challenges, and areas that are still not fully understood. The panel explained that while work on the DPM is slowing, other population‑estimation research is continuing at full strength, particularly improvements to admin data sources such as SPD and demographic indices, which remain essential. Discussion then moved to the wider context of future censuses, with some participants noting that the long‑term direction depends heavily on whether censuses continue beyond 2031. This shift in priorities was announced in March 2025 as part of the Population and Migration Quarterly Update. The panel highlighted that the 2031 census provides a perfect calibration point and that slowing work too much could repeat the uncertainty experienced before the 2031 decision. The panel agreed that while the future of the DPM is not fixed, the organisation must keep an open mind, fully explore alternative methods, and ensure that decisions are based on robust evidence. There was broad consensus that the census remains a valuable input to population modelling, and that future planning should be proactive rather than reactive. The session concluded with reassurances that admin‑data research will continue, the overall work plan will be articulated more clearly, and further updates will be shared as evidence develops. 

Technical Manual for Admin-Based Population Estimates produced using the Dynamic Population Model – presented by Pratibha Vellanki/Emma Ward/Andrew Taylor ONS 

An overview of the draft comprehensive methods guide developed in response to OSR technical requirements was presented, explaining how the guide, vignettes and supporting tools are version‑controlled within an R package and intended to demystify the DPM. The guide will be made publicly available as a GitBook and includes layered explanations for different audiences, from introductory plain‑English summaries through to full mathematical detail, code snippets and model evaluation. It also contains minimum data requirements, detailed modelling descriptions, reproducibility information, and example datasets. Tutorial vignettes guide users through setting up data, running models and evaluating outputs, with worked examples demonstrating Bayesian modelling workflows, diagnostic checks and interpretation. Additional chapters document package versions, underlying data sources, model specifications and technical implementation to support transparency and reproducibility. The team emphasised that this is an early draft, with some sections still being refined, diagrams to be added and formatting to be improved. In conclusion, the aim is to provide a clear, accessible and comprehensive guide that supports both internal training and external understanding of the DPM. 

Overview of ONS Alternative methods innovation exploration (plus discussion) – presented by Joe Southam-Gisby ONS

The presentation outlined the work underway to explore alternative population‑estimation methods following the pause in DPM development. It was explained that while most DPM work has paused, documentation and the Gitbook remain active, and the focus has now shifted to identifying and testing other viable approaches. The team has been commissioned to investigate a broad range of methods and data options, recognising that previous work may have been too narrowly focused on the DPM. ONS hosted an internal workshop with colleagues, generating a wide set of ideas, forming an early longlist of potential methods and data sources. The team emphasised that all ideas remain in very early stages and nothing has been ruled out, given changes in data access, technology and organisational capability since the DPM was originally commissioned. The purpose of presenting these ideas to the panel was to gather reactive feedback, highlight any clear issues or opportunities and identify areas the team may not yet have considered.

The panel discussed the presentation on alternative population‑estimation methods and the broader implications of pausing DPM development. Members agreed that a high‑level paper would be valuable to outline the proposed approaches, associated assumptions, timelines and decision‑making criteria. Several participants noted the importance of considering legislative requirements for more ambitious options and the need for long‑term planning if such options are pursued. The group emphasised that any methodological choices must account for UK‑wide cohesion, recognising that Scotland and Northern Ireland may not have access to the same data sources and that divergence in methods could affect comparability and resource allocation. This criterion should be explicitly included in future assessment frameworks. 

Participants requested that the forthcoming paper include a clear explanation of the current population‑estimation process and data inputs, to help clarify where improvements are needed. There was discussion about whether the objective is to replace the census, replace mid‑year estimates, or address both; this remains an area the team is still exploring. The panel also asked that the paper outline methodological limitations such as the explainability challenges associated with neural‑network or deep‑learning methods and distinguish between approaches driven by known weaknesses (reactive) and those intended to support longer‑term strategic improvements. 

Action:

ONS to circulate viability paper for shortlisted methods to panel members for comment. 

The panel suggested the potential value of wider academic involvement, such as open calls to universities or commissioning PhD‑level research, to bring in innovative approaches and independent evaluation. This was recognised as a potential route to expand the evidence base beyond what can be achieved in‑house. 

The panel agreed that a shortlist of candidate methods should be circulated as part of the planned paper, allowing members to comment before proof‑of‑concept work begins. It was suggested that the next panel meeting should be scheduled for late May or early June to allow meaningful review of progress. The group discussed the importance of issuing the paper for written feedback in advance, rather than only presenting it during a meeting. 

Members also raised the need for evaluation criteria to be finalised before proof‑of‑concept work begins. It was noted that another team is developing “statistical goals” that will define what a successful population‑estimation method should achieve; although still in draft, these are intended to serve as the evaluation framework. The panel suggested that the evaluation criteria should be issued as a separate paper, as they underpin future decisions and may be relevant beyond this specific project. The panel noted that they would want to see these goals to understand what ONS is trying to achieve.  

Action:

ONS to circulate statistical goals to panel members for information. 

Any other business – Prof. Ana Basiri (Chair) 

The chair confirmed that the minutes will be shared with panel members before publication on the UKSA website.  

The chair thanked the group for their contributions and noted that the next meeting will likely take place in June.