adding ABtestingpy

Author: CamDavidsonPilon

ExamplesFromChapters/Chapter2/ABtesting.py

@@ -0,0 +1,41 @@
+"""
+This is an example of using Bayesian A/B testing
+
+"""
+
+import pymc as mc
+
+#these two quantities are unknown to us.
+true_p_A = 0.05 
+true_p_B = 0.04
+
+#notice the unequal sample sizes -- no problem in Bayesian analysis.
+N_A = 1500
+N_B = 1000 
+
+#generate data
+observations_A = mc.rbernoulli( true_p_A, N_A )
+observations_B = mc.rbernoulli( true_p_B, N_B )
+
+
+
+#set up the pymc model. Again assume Uniform priors for p_A and p_B
+
+p_A = mc.Uniform("p_A", 0, 1)
+p_B = mc.Uniform("p_B", 0, 1)
+
+
+#define the deterministic delta function. This is our unknown of interest.
+
+@mc.deterministic
+def delta( p_A = p_A, p_B = p_B ):
+    return p_A - p_B
+
+
+#set of observations, in this case we have two observation datasets. 
+obs_A = mc.Bernoulli( "obs_A", p_A, value = observations_A, observed = True )
+obs_B = mc.Bernoulli( "obs_B", p_B, value = observations_B, observed = True )
+
+#to be explained in chapter 3. 
+mcmc = mc.MCMC( [p_A, p_B, delta, obs_A, obs_B] )
+mcmc.sample( 20000, 1000)