Common Questions

What does MRP stand for in polling?: Multilevel Regression and Post-stratification. It combines a national survey sample with local demographic data to project seat-by-seat results rather than just national vote shares.
How accurate is MRP polling?: YouGov's MRP has come within five seats of the final result at every UK general election since 2017, giving it a strong track record in first-past-the-post elections.
What does the Senedd 2026 MRP project?: YouGov's MRP projects Plaid Cymru on 43 seats, Reform UK on 30, Welsh Labour on 12, Greens on 10 and Welsh Conservatives on 1 in the 96-seat Senedd.
What does the Scotland 2026 MRP project?: Electoral Calculus (7 April 2026) projects the SNP on 67 seats — two above the 65-seat majority threshold — with Reform UK on 14 regional seats and the Conservatives falling to 9.
Who produces MRP polls for UK elections?: YouGov, Electoral Calculus, and More in Common are the main producers. Academic teams at universities also produce MRP models for research purposes.

Background

Multilevel Regression and Post-stratification (MRP) is a statistical polling technique that combines a large national survey with granular demographic data to estimate vote shares at the constituency or ward level. Unlike standard national polls, MRP produces seat-by-seat projections rather than headline vote shares. The technique has become central to UK election forecasting: YouGov has used it at every UK general election since 2017, coming within five seats of the final result each time. It is also used by Electoral Calculus, More in Common and academic teams.

In the lead-up to the 7 May 2026 elections, two MRPs are particularly significant. YouGov's 2026 Senedd MRP projects Plaid Cymru on 43 seats, Reform UK on 30, Welsh Labour on 12, the Greens on 10 and the Welsh Conservatives on 1 — the first time Plaid would be the largest Senedd party. Electoral Calculus published a Holyrood MRP on 7 April 2026 (4,105 respondents, fieldwork 13-31 March) projecting the SNP on 67 seats, two above the 65-seat majority threshold, with Reform on 14 regional seats and no constituencies. MRP models are probabilistic: they show the most likely seat distribution given current polling, not a guaranteed outcome.

MRP matters in 2026 because it translates fractured national polling — five parties above 10 per cent — into actionable seat projections that parties use for resource allocation and tactical campaigning. Without it, both Plaid's Welsh plurality and Reform UK's Holyrood regional presence would remain conjectural; with it, campaign teams can target specific marginal seats that the aggregate national numbers obscure.

How the World Sees Them

SNP

A 67-seat projection at Holyrood would be the first outright SNP majority since 2011 — John Swinney has said such a result would constitute a fresh mandate for a second independence referendum.

Plaid Cymru

MRP projections showing 43 Senedd seats represent a historic result if accurate; the party has never led the Senedd.

Polling sceptics

MRP requires assumptions about demographic voting patterns that may not hold when the electoral system itself (as in Wales) has fundamentally changed since the model was trained.