To-hit probabilities can be determined from hit ratios. Assuming we hit p*N times out of N, the 95% confidence interval would be (from http://www.dianthus.co.uk/statistics/confidence.htm):
p +/- 1.96*sqrt(p(1-p)/N)
To get 95% confidence in an error of +/- (100*e)%, we'd need:
e >= 1.96*sqrt(p(1-p)/N)
N >= 3.8416*(p - p^2)/e^2
Probability +/- 0.5% +/- 1% +/- 2% +/- 5% 0.10 13830 3457 864 138 0.20 24586 6147 1537 246 0.30 32269 8067 2017 323 0.40 36879 9220 2305 369 0.50 38416 9604 2401 384 0.60 36879 9220 2305 369 0.70 32269 8067 2017 323 0.80 24586 6147 1537 246 0.90 13830 3457 864 138
The following table of z-values (from http://people.hofstra.edu/faculty/Stefan_Waner/RealWorld/finitetopic1/confint.html) can be replaced for the 1.96 above to calculate other confidence sample sizes (for more on z-values see http://www.fourmilab.ch/rpkp/experiments/analysis/zCalc.html):
Z confidence level 1.282 80% 1.645 90% 1.960 95% 2.326 98% 2.576 99% 3.090 99.8% 3.291 99.9%
Last modified: Tue, 4 Jul 2006 06:40:09 GMT
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