pymc-devs/pymc — pull request #661 by twiecki (2014-12-17 07:31:05+00:00)
Title: Change NUTS average acceptance ratio to 0.8

Stan changed their target acceptance ratio of the NUTS sampler recently to 0.8:
https://twitter.com/betanalpha/status/537574485302714368
because of strong theoretical considerations:
http://arxiv.org/abs/1411.6669