Wednesday, January 25, 2012


How can journalists make such whoppers as this statement:
The survey, conducted under contract by Kelton Research, asked multiple-choice questions via the Internet of 1,000 people ages 16 to 25, selected to be nationally representative, with a 95 percent confidence level.
uh, 95% confident to what level? 2 percent? 5 percent? I suppose you could work it out from the sample size, lets see:
Sixty percent of respondents ages 16 to 25 to the Lemelson-MIT Invention Index, which seeks to gauge innovation aptitude among young adults, named at least one factor that prevented them from pursuing further education or work in science, technology, engineering and math fields
So the standard error for that proportion is sqrt(0.6*(1-0.6)/1000) or 1.5%, so a rough 95
% confidence interval is plus or minus 3%.   That wasn't so hard, was it? 4 extra words.

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