  In this paper, we propose an explicit closed-form Bayes factor for the
problem of two-sample hypothesis testing. The proposed approach can be regarded
as a Bayesian version of the pooled-variance t-statistic and has various
appealing properties in practical applications. It relies on data only through
the t-statistic and can thus be calculated by using an Excel spreadsheet or a
pocket calculator. It avoids several undesirable paradoxes, which may be
encountered by the previous Bayesian approach of Gonen et al. (2005).
Specifically, the proposed approach can be easily taught in an introductory
statistics course with an emphasis on Bayesian thinking. Simulated and real
data examples are provided for illustrative purposes.
