def get_interval_z_prob(low_z,high_z):
"""Get the probability of a range of z scores
"""
if low_z > high_z:
raise ValueError(\
"lower z value low_z must be lower than upper bound z value high_z. Were parameters reversed?")
#The low z represents a lower deviation from the mean,
# and so will produce the higher probability
high_prob = z_high(low_z)
low_prob = z_high(high_z)
interval_z_prob = high_prob - low_prob
return interval_z_prob
def z_tailed_prob(z, tails):
"""Returns appropriate p-value for given z, depending on tails."""
if tails == 'high':
return z_high(z)
elif tails == 'low':
return z_low(z)
else:
return zprob(z)
def test_z_high(self):
"""z_high should match R's pnorm(lower.tail=FALSE) function"""
negprobs = [
0.5000000, 0.5039894, 0.5398278, 0.6914625, 0.8413447,
0.9772499, 0.9999997, 1.0000000, 1.0000000, 1.0000000,
1.0000000, 1.0000000,
]
probs = [
5.000000e-01, 4.960106e-01, 4.601722e-01, 3.085375e-01,
1.586553e-01, 2.275013e-02, 2.866516e-07, 7.619853e-24,
2.753624e-89, 4.906714e-198, 0.000000e+00, 0.000000e+00]
for z, p in zip(self.values, probs):
self.assertFloatEqual(z_high(z), p)
for z, p in zip(self.negvalues, negprobs):
self.assertFloatEqual(z_high(z), p)
