Bottlebank said:
At the moment around 1.5% of cavers (most of who probably would be entitled to a vote in the actual referendum) have voted, based on a total of 6000 or so BCA members. In percentage terms this is probably far higher than opinion polls on general elections for example.
Bit of a red herring, of course. When the sample size (no. voting in the ukc poll) is low compared with the population size (total no. of BCA members), the 'error" in the sample poll compared with the "true" result depends on the proportion of the sample voting yes or no, and the sample size, and not on the proportion of the population that the sample comprises. Counter-intuitive, I know.
Biggest source of error is going to be whether the sample is a random sample of the population, which is highly questionable when the people answering a poll are self-selected, quite apart from whether people on ukc are typical of BCA members.