def FeldmanCousins(this_ctr, total_ctr, confidence_interval):
from ROOT import TEfficiency
k = TEfficiency()
eff_mean = float(this_ctr) / float(total_ctr)
eff_upper = k.FeldmanCousins(total_ctr, this_ctr, confidence_interval,
True)
eff_lower = k.FeldmanCousins(total_ctr, this_ctr, confidence_interval,
False)
return eff_mean, [eff_lower, eff_upper]
import sys
from ROOT import TEfficiency
if (len(sys.argv) != 3):
print
print 'USAGE : python FCstats.py Ntotal Npass'
print
exit()
tot = int(sys.argv[-2])
passing = int(sys.argv[-1])
k = TEfficiency()
k.SetStatisticOption(TEfficiency.kFFC)
# get +/- 1 sigma interval from Feldman Cousins statistics
eff = passing / float(tot)
eff_upper = k.FeldmanCousins(tot, passing, 0.6827, True)
eff_lower = k.FeldmanCousins(tot, passing, 0.6827, False)
print 'Efficiency : %.03f.' % (eff)
print '1-sigma interval : [%.03f, %.03f]' % (eff_lower, eff_upper)
