Posted by
Richard Ristow on
Oct 24, 2014; 10:43pm
URL: http://spssx-discussion.165.s1.nabble.com/chi-square-but-very-disparate-sample-sizes-tp5727676p5727694.html
At 02:28 PM 10/22/2014, sgthomson99 wrote:
>If Population A is 4000 patients and there are 3.2% with the flu,
>and Population B is 53500 patients and 3.9% have the flu, is the
>difference in prevalence of the flu significant or not?
One more consideration: the chi-square is based on the assumption
that different individuals' contracting the flu are statistically
independent events.
I don't know details of influenza epidemiology, but it is a readily
transmissible infection, and a difference in rates could be due to
random events that affect a number of people together: for example, a
cluster around one case who'd been out and around and infected a good
many other people.
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