Sample Size Determination in Bayesian Statistics-A Commentary

I wish to thank the Editor of The Statistician for inviting me to write this commentary which addresses not only the specific results obtained by Joseph et al. (1995) but also some related results presented by other researchers. Joseph et al. (1995) have written quite an interesting paper on sample size in a Bayesian context, which contributes significantly to the on-going discussion on this topic. As mentioned by Adcock (1992) the determination of sample size is an important question for the applied statistician. Although this question has been of interest for a long time in classical frequentist statistics, it seems to have attracted the attention of Bayesians only quite recently; the reasons could be those mentioned by Pham-Gia and Turkkan (1992). The most complete treatment to date on classical sample size methodology seems to be Desu and Rhagavarao (1990) where the Bayesian approach is barely mentioned. A list of useful sample size tables can also be found in that work.