Since I posted the graph on the opinion poll data on the Independence Referendum in Scotland I’ve had some questions on both twitter and facebook (mainly from two of my three brothers still living in Scotland, one a clear Yes voter and the other undecided).

I was asked whether leaving out the undecideds was skewing the result that I was showing. My initial response to this was that it wasn’t, the analysis was looking at how the proportion of those deciding to vote was changing in favour of Yes. However I thought that I would go back and do the three way look at things and see if that gave a different picture.

Clearly the visual is very different, partly my choice in how to present it. However the story it tells is not different from the one I produced a couple of days ago. On the face of it the combined trend for Yes is growing faster than that for No, and people can be clearly seen to be making up their minds about how to vote. The margin between Yes and No is smaller than the total number of undecided people and when you also take into account the error margins it becomes rather too close for comfort regardless of which camp you might sit in. Both of the dotted lines show the general trend for the respective Yes & No scores for the opinion polls, and sit in the middle of the band of outcomes that individual polls have reported. So while No appears to be clearly above Yes, in reality there is a small overlap between the lower bound of No and the upper bound of Yes. The graph below shows this more clearly.

IndyRef Polls2012-2014 All detail v2

On balance a No vote is more likely than a Yes vote, but with just over a week to go and some strange behaviour in the media (their unconvincing stunt on the Last Queen of Scotland being evidence of them not letting a good story get in the way of scaring people to vote no) it can easily change.

If you are interested in knowing more about the opinion polls and what the people of Scotland (not all of whom are actually Scottish) think about things then is a good place to start (with thanks to my other brother who pointed it out after I’d done all the hard work).