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# File 'lib/fluent/plugin/log-likelihood.rb', line 4
def getChiSqrScore (countNew,totalNew,countOld,totalOld)
countNew = countNew.to_f
countOld = countOld.to_f
totalNew = totalNew.to_f
totalOld = totalOld.to_f
p = countNew/ totalNew
q = countOld / totalOld
if ( p < q )
return 0
end
t = (countNew + countOld) / (totalOld + totalNew)
if ( t == 0)
return nil
end
v = countNew * Math::log(p/t) + countOld * Math::log(q/t)
if ( t == 1 )
return Statistics2..chi2X_(1,2*v)
end
if ( p < 1)
v = v + ((totalNew - countNew) * Math::log((1-p)/(1-t)))
end
if ( q < 1)
v = v + ((totalOld - countOld) * Math::log((1-q)/(1-t)))
end
return Statistics2.chi2X_(1,2*v)
end
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