Merge pull request #954 from pymc-devs/nuts_acceptance

Changed default NUTS acceptance to 0.65

Author: Chris Fonnesbeck

pymc3/step_methods/nuts.py

@@ -45,7 +45,7 @@ def __init__(self, vars=None, scaling=None, step_scale=0.25, is_cov=False, state
                 state to start from
             Emax : float, default 1000
                 maximum energy
-            target_accept : float (0,1) default .65
+            target_accept : float (0,1) default .8
                 target for avg accept probability between final branch and initial position
             gamma : float, default .05
             k : float (.5,1) default .75