TacticalVote.scot has commissioned a data analyst to analyse polling data to ascertain whether a vote for All For Unity risks reducing the overall number of unionist seats as they were won in 2016.

Our data analyst has built a swingometer which projects the results of the 2016 election if Alba and All For unity had stood.

We included Alba because it is another new party standing on the list which has the potential to alter significantly the allocation of seats. We assume zero seat movement in the constituency seats.

For each region, the swingometer allows you to choose what size swing you want modelled – anything from 0% to 30%. The swing measured is from the main unionist parties plus UKIP to All For Unity and from SNP and Green to Alba.

Once you’ve set the swingometer, the results are displayed. They calculate the seat distribution using the proportional representation d’Hondt method (to understand how d’Hondt works, see here). We display seat changes via a simple chart as well as a table of results.

Our analyst has run the model 4,500 times for different regions and different swings between 0% and 30%. The table below summarises the results. Green boxes show projections with more seats for unionist parties, yellow boxes no change and red boxes a net loss for unionist parties.

Green: unionist vote gains seats Yellow: unionist vote see no gain or loss in seats Red: unionist vote loss in seats

Contrary to the Scottish Conservative Party analysis which used 96 projections at a completely unrealistic 40% swing, our much bigger analysis shows that 63% of outcomes shows increased unionist seats, 20% preserves the 2016 status quo and 17% shows a net loss of unionist seats. The charge that voting for All For Unity will always cost unionist seats is demonstrably false; more than 4 projections out of 5 show no loss, with 6 out of 10 showing a gain.

The swingometer shows conclusively that voting for All For Unity will very significantly increase the probability of returning more unionist MSPs to Holyrood and reducing the risk of a pro-independence majority.

Many of the projections clearly show Alba taking seats off the Greens, while All For Unity also predominantly takes seats off the Greens. This is unsurprising as these three parties will win the lowest number of votes and be competing with each other for the last, or last two, seats on the list.

A key assumption in this swingometer (as with others) is that constituency seat results stay the same as in 2016. This ignores the impact of tactical voting, which has never been so widely promulgated as in this election. Numerous websites have sprung up such as this site. Indeed the need – and rationale – for tactical voting is what prompted George Galloway to found A4U, with the Daily Mail running a daily series on tactical voting for each constituency.

However, if tactical voting is widely adopted, it will increase the number of seats won by the main unionist parties. In turn, this will make it harder for the main unionist parties to win list seats and will increase the wins for All For Unity.

Brian Henderson

Data Analyst & A4U candidate

Brian Henderson BSc has spent 40 years working in information technology (IT) with billions of data records. He spent 12 years as a leading scientific civil servant at Harwell, Oxford and 28 years as a European IT expert in multiple fields including financial planning and analysis and ITIL (help desk provision and system administration). He worked in the world-wide web development for business, including the first UK web server, as well as being an early lead in social media adoption with significant contributions to facebook and beta-testing twitter.

The swingometer shows conclusively that voting for All For Unity will significantly increase the probability of returning more unionist MSPs to Holyrood and reducing the risk of a pro-independence majority.