A Little Christmas Treat

In an earlier post, I assessed the potential utility of Ratio Swing (RS) as an alternative method to Uniform National Swing (UNS) of projecting opinion poll results to potential seat implications for both Westminster and the National Assembly. I suggested that there was no clear empirical or conceptual advantage to either method. I have continued to use UNS, as the ‘industry standard’ method, in the seat projections I do for ITV-Wales from our Welsh Political Barometer polls. But I also promised, as a special treat, to produce RS results for the cognoscenti who read this blog. Here, as a little Christmas treat, are the figures for the most recent Barometer poll.

To remind you, the latest Barometer poll produced the following voting figures for Westminster:

Labour: 36%
Cons: 23%
UKIP: 18%
Plaid Cymru: 11%
Liberal Democrats: 5%
Greens: 5%

Assuming UNS from the 2010 result, this produces the following projected outcome for the next general election:

Labour: 28 seats (+2)
Cons: 8 seats (no change)
Plaid: 3 seats (no change)
Lib-Dems: 1 seat (-2)

The specific seats to change are: Cardiff Central (won by Labour from the Liberal Democrats); Cardiff North (won by Labour from the Conservatives); and Brecon and Radnor (won by the Conservatives from the Liberal Democrats).

Are there any differences if we model the changes since 2010 as RS instead of UNS? Well, these are the overall projected results:

Labour: 28 seats (+2)
Cons: 8 seats (no change)
Plaid: 4 seats (+1)
Lib-Dems: 0 seats (-3)

There is only one seat where the different method produces a different result: Ceredigion, which is now projected as a gain for Plaid Cymru.

Before Plaid supporters start getting too excited – it seems very unlikely to me that support for the Liberal Democrats will really see their vote slip by three-quarters across the board, as implied by RS. As I’ll discuss in a future blog post, it seems far more plausible that the Lib-Dems will fall away very substantially in the many Welsh seats that they don’t hold, but be much more resilient in their existing strongholds.

And for the National Assembly? The Barometer figures were:

Constituency Vote List Vote
Labour 35 31
Conservative 22 20
Plaid Cymru 19 19
UKIP 12 15
Lib-Dems 6 6
Greens 5 7
Others 1 2


On these figures, UNS would project only two constituency seats to change hands from May 2011: the Liberal Democrats would regain Cardiff Central from Labour, while Labour would also lose Llanelli to Plaid Cymru. Taking into account both the constituency and list results, UNS produces the following projected seat outcome for a National Assembly election:

Labour: 28; 26 constituency AMs, 2 list AMs
Conservative: 12; 6 constituency AMs, 6 list AMs
Plaid Cymru: 10; 6 constituency AMs, 4 list AMs
UKIP: 7 (+7); all list AMs
Liberal Democrats: 2; 2 constituency AMs
Greens 1; a list AM (in Mid and West Wales).

What about RS? This also projects only two constituency seats to change hands on 2011. One is again Llanelli; but other one is Brecon and Radnor – again showing how RS currently tends to project a worse Lib Dem performance.

The overall outcome suggested by RS is:

Labour: 29; 27 constituency AMs, 2 list AMs
Conservative: 12; 7 constituency AMs, 5 list AMs
Plaid Cymru: 10; 6 constituency AMs, 4 list AMs
UKIP: 7 (+7); all list AMs
Greens 2; 2 list AMs (in Mid and West Wales, and South-Wales Central)

While the Lib-Dems are wiped out completely.

UNS and RS offer slightly different ways of projecting the broad implications of current polling results. Neither are likely to be perfect predictors of future election results: there will be some changes in the support levels of parties between now and the elections; moreover, neither method makes any attempt to take account of local factors that may cause significant deviations from the overall nation picture. But UNS and RS provide us with at least a baseline against which we can judge local deviations, and a broad gauge of how the parties stand now.

Postscript: I was asked on Twitter by Gethin James of UKIP for the detailed UNS and RS projections for Ceredigion. So, with the reminder that these figures are not my predictions for what will happen in Ceredigion in May, here they are:


LibDems: 34.9%

Plaid: 28.0%

UKIP: 18.2%

Conservatives: 8.5%

Greens: 6.4%

Labour: 5.6%



Plaid: 27.5%

Greens: 22.5%

UKIP: 19.5%

LibDems: 12.5%

Conservatives: 10.7%

Labour: 5.7%


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