How to pick the number of topics with Umass measure?

[guntherzhao]

I am trying to use Umass measure to pick the best number of topics, but I do not know what Umass exactly means? About the coherence score, is it the bigger, the better, or just the opposite? Below is the output of my test with Umass measure. How many topics should I pick?

[dean-rahman]

The bigger the better.
From what py file are you pulling you evaluate() function?