ReadWriteWeb’s coverage of a new study on webmail demographics contains one sentence that left me a little confused:
Gmail, for instance, includes more females (53%) than males (47%). If those were election poll results, we would call it “too close to call,” but in terms of tens of thousands of users, these percentage point differences have meaning.
If a 53/47 outcome isn’t clear when drawn from millions of election returns, how can it possibly be sufficient when taken from a sample measured only in the tens of thousands?
{ 2 comments… read them below or add one }
they’re not taken from election returns.
demographic election data comes from exit polling, not the ballots themselves.
That’s true, but the quote refers directly to “election poll results” (i.e. votes) themselves, not election demographic data, as I interpret it.
Even if that were not the case, exit poll samples are numbered in the low tens of thousands (I believe CNN had n~20,000 for the 2008 presidential election), which would yield a margin of error not dramatically different from this study. Despite having far fewer responses, once you get into numbers this high the confidence is quite large: n=20,000 has a 99% margin of error (for a 53% statistic) of 0.9% and n=120,000 has a 99% margin of error of 0.4%. Naturally, that assumes a perfect sampling distribution which neither the internet survey nor the election polls were fortunate enough to have.