Lib Dem support at local elections
I'd have several comments here (and seen countless similar comments on Twitter) asking why, if the Lib Dems got 16% in the local elections this month none of the polls show them with that level of support. They normally proceed to conclude that the polls are wrong.
As I'd said several times here before, people vote differently in local elections than they do in general elections, so polls asking how people would vote in a general election are not a good guide to how they would vote in a local election (and conversely, how people vote in a local election is not necessarily a good guide to how they would vote in a general election).
Anyway to try and finally nail down this nonsense, below is a graph comparing what the Liberal Democrats got in local elections since 1992, and what opinion polls of general election voting intention were showing. Local election figures are the Rallings and Thrasher National Equivalent Vote for each year (you'll note that 1997 and 2001 are missing, since as far as I can tell R&T did not produce a NEV figure for those years. I have not yet seen the R&T figures for 2012), polling figures are the average Lib Dem score in polls from all companies in the first four months of each year.
As you can see, the contrast between what the Liberal Democrats manage in general election voting intention polls and what the Liberal Democrats achieve in local elections is not new - it has been consistent for the last twenty years. While the gap has gotten bigger and smaller over the years, peaking during the 90s and at its smallest during Cleggmania, on average Liberal Democrat support has been seven points higher in local elections than what they were polling at the time. Over the same period, polls have been largely accurate in predicting Liberal Democrat support at general elections, with the exception of 2010 when they over-estimated Lib Dem support.
In short, the difference between Lib Dem support at local elections and national polls is normal, and Lib Dem performance at the 2012 local elections is wholly consistent with their current ratings in general election polls.
