There was a similar phone/online polling divide at the last national UK referendum
Phone polls trounced online ones in the 2011 AV vote
I get asked several a week at the moment for a view on online phone divide that we’ve seen over the EURef. Which is better I’m asked and I’m reluctant to come down on one side or the other.
At the general election the final polls from both modes were in the same ball park although during the official campaign period the phone firms were much more like to report CON leads than online ones.
But in any case general election polling to determine party shares is very different from the binary choice in a referendum. There should be fewer complications with the latter.
So I’ve dug our the data about the last UK referendum to see if there is anything to learn and, remarkably, they had the same mode split then as well.
The chart above I’d based on the average NO2AV lead in the final polls years ago. Then the phone pollster trounced the online ones.
Maybe that is happening this time as well. Maybe not.