Scottish Referendum – Prediction on 14th of September

This is a Forward Looking prediction. This means it is a forecast of what the Yes vote will be on the 18th of September.

The Point in Time “centre point” of the prediction is 48.95%. This is the middle point of the distribution of likely outcomes based upon recent polling and other market data. This prediction is up over 1.5% from yesterday.

The Point in Time “Probability of Yes being greater than 50%” prediction is 34.66%.  This means that when we run 10,000 simulations of the referendum based on current polling trends and the variances within them, Yes would win 3,466  times. This prediction is up almost 25% from yesterday.

The table below shows the 50% and 95% confidence intervals for the Yes vote.

Date Yes% 50% Intervals 95% Intervals
11th September 48.18 47.14 – 49.23 45.15 – 51.21
12th September 47.82 46.76 – 48.88 44.74 – 50.91
13th September 47.40 46.16 – 48.64 43.80 – 51.00
14th September 48.95 47.60 – 50.31 45.02 – 52.89

Why the large movement today?

We take into account not just the most recent opinion polls but also the overall trajectory in recent days. Last night’s polls indicate that there is a movement back in support towards “Yes”.

We have not seen the data-tables yet for the ICM and Panelbase polls, so when the available data from these polls is richer our forecast my adjust further.

What about that large ICM Yes lead yesterday?

The ICM poll overnight was one of four, and the only one to show a Yes lead. It was also a different sample methodology than previous ICM polls, and a smaller size (700).

Our analysis shows that the ICM poll is right at the upper end of where we believe the true Yes figure currently lies. It is what we call “an outlier”.

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