BCal help system: The Tutorial
If you select "Show me" now, you will see our summary of the results from three different runs of BCal with different seeds for the pseudo random number generator. We can see that, in general, the HPD regions produced from each run are very similar to one another. In fact, there is only one parameter for which the variability in the posterior estimates cannot reasonably be explained by the large errors on the radiocarbon determinations themselves (there are several at this site greater than 100) and the variability in the calibration curve. The rogue parameter is alpha 1 and we will focus on this parameter and why we are not surprised about this result in the next page of the tutorial. First, we would like to encourage you to think about the other parameters which are the ones of greatest interest to the archaeologists at the fishpond site.
Taking a close look at the 95% HPD regions in the frame above, you will
see that for all the thetas, phi 1 and beta 1/alpha 2 the three runs have
produced results which are very similar. Indeed, given the large
errors on the determinations from this site (some of them are over 100)
and the nature of the calibration curve, we consider these results to be
extremely similar. Since they are not identical, however, it is important
that we report the results from just one run (don't be tempted to do any
kind of averaging or to `pick and choose' the results you like best!)
and acknowledge the level of between run variability in any report or paper
we write that includes them.