Reply to thread

Message: <blockquote data-quote="sumone" data-source="post: 1232422" data-attributes="member: 551481">Are you looking for variance or standard deviation?if variance, take the mean of all trials; call it M.add the total of (M-nT)^2 where M is the mean you just found &amp; nT is the value for trial "n"divide this total by number of trials minus 1 (n-1, since I'm guessing this is an unbiased calculation)that gives you the mean(average) variancetake the square root if you want standard deviation.ex:n1 = 1, n2=2, n2=3M = (1+2+3)/3 = 6/3 = 2(M-n1)^2 + (M-n2)^2 + (M-n3)^2 = (2-1)^2 + (2-2)^2 + (2-3)^2 = 1 + 0 + 1 = 2divided by n-1 = 2 / (3 - 1) = 2/2 = 1</blockquote>

Top