Northern Ireland Polling Error Analysis
Below are the summary results of running 1000 simulations of the Northern Ireland Assembly election using our Margin of Error preset. It uses randomised vote shares centred around the current polling average shown in our Nowcast. It then applies a further layer of variation by tweaking every party's swing in every constituency based on local factors, including average income, urban/rural and whether it is east or west of the Bann.
This aims to demonstrate the degree of uncertainty that's inevitable in election projections and show how even small polling errors, regional factors or candidate effects can lead to significantly different outcomes. In many cases the difference between an excellent year for a party and a terrible year is well within a normal polling error.
Results are based on latest polling and are updated regularly. The most recent update was on 9 October 2025
Seat Distribution by Constitutional Position
This chart shows the distribution all Unionist, Nationalist, and Other seats across 1000 simulations. The majority line of 46 is included to show how likely (and unlikely) it is that any bloc wins a majority.
The Unionist bloc combines the DUP, UUP, and TUV, the Nationalist bloc is made up of Sinn Féin, SDLP, and Aontú. The Other bloc is defined as Alliance, PBP, Green, Independent, and Other.
Hover over the points to see how often each bloc won that number of seats.
It should be noted that the most likely independent to be elected is Clare Sugden, a Unionist, and People Before Profit advocate for a United Ireland but reject the label of Nationalist.
Seat Distribution by Party
The following charts show the distribution of outcomes for each party across all 1000 simulations. Taller peaks indicate more likely outcomes while 'tails' indicate extreme outcomes which would require large polling errors. The dashed line shows the Nowcast prediction for comparison.
Hover over the points to see how many times each occurred out of the 1000 simulations. There tends to be less variation amongst very small parties as there are fewer places in which they have a reasonable chance of winning a seat.
Having a tall but narrow disritubution means that a party has several solid seats which are very safe but weaker elsewhere. This can prevent them from falling too far but also means that growth is difficult.
A shorter, broader distribution means that a party has a mix of seats which are safe, at risk, and in with a chance of gaining. This can allow for growth but also puts them at risk of collapse.
Seat Probabilities
Each square represents a seat. Seats are ordered by the likelihod that the given party will win it. Darker squares indicate safer seats, medium coloured squares indicate battleground seats, whilst very light coloured seats would require a big polling miss for that party to win.
Hover over a square to get the percentage of times that party won the seat across 1000 simulations.
Sinn Féin33 potential seats
DUP28 potential seats
Alliance21 potential seats
UUP21 potential seats
SDLP17 potential seats
TUV17 potential seats
PBP5 potential seats
Green4 potential seats
Independent2 potential seats
Aontú1 potential seat
This simulation uses a normal distribution of errors from the polling average which means that parties are just as likely to overperform as they are to underperform their average. The vast majority of misses will have each party's vote share within 2% of the Nowcast but there will be some rare instances where the misses are much larger. The bigger the miss, the less likely it is to occur. This means that most results stay close to current polling averages, but occasional larger deviations are possible. This analysis will be updated as new polls arrive.