On Fri, Nov 10, 2006 at 03:55:26AM +0100, Segher Boessenkool wrote: > > p = probability of success = .997 (897 / 900) > > q = probability of failure = .003 (1.0 - .997) > > n = number of trials = 2323 > > X = number of successes = 2323 > > > >Applying these to the binomial probability formula, we get: > > > > P(2323) = 2323! / ((2323 - 2323)! * 2323!) * .997**2323 * .003** > >(2323-2323) > > = .0009307922 > > > >So we conclude that the probability that our trials with this patch > >applied achieved exactly 2323 successes because of chance alone is . > >0009. > > Not prematurely rounding p to a useless precision gives you > > p**2323 ~ 0.000428
Sure. I just rounded early because most online tools that people would use to verify the calculation cannot deal with the higher precion. > even. And that just calculates the chance that 2323 tries all > succeed given that the chance for one to succeed is 897/900; it > doesn't compare two hypotheses at all. What? The null hypothesis is that this patch has no effect. Since the probability of observing 2323/2323 successes is .000428, we reject the null hypothesis under a 95% confidence interval. No? _______________________________________________ Xen-ppc-devel mailing list Xen-ppc-devel@lists.xensource.com http://lists.xensource.com/xen-ppc-devel
