That seems to be a pretty sound approach, compared to some of the stuff about multiarmed bandits that shows up here some times. And I certainly expect Noel Welsh to chime in as well.

There are two schools of thought about the approaches to sequential testing, the Bayesian approach lead by Anscombe, and the frequentist by Armitage. I talked a bit about this and outlined Anscombe's approach here [1]. And it is great to see such a nice write up of the frequentist approach and the tables of the stopping criteria

[1] http://blog.custora.com/2012/05/a-bayesian-approach-to-ab-te...