a jump in BF after increasing the number of participants
We have conducted an experiment in which we continuously increased the number of participants, and every once in a while examined the Bayes factor. We decided to stop the recruitment once the BF reached a substantial conclusion (BF higher than 3 or lower than 1/3), thus supporting one of two hypotheses (H1 or H0).
In practice, what happened is that for a while (until recruiting approximately 400 participants) the BF ranged between 1 and 2, providing inconclusive results again and again. In the ninth iteration of subjects' recruitment (after adding 50 more participants), the BF increased substantially (BF= approximately 11 in favor of H1).
Is such a jump common in Bayesian hypotheses testing? If so, is there an analytical explanation for why such jumps in the value of the BF occur?
Thank you very much,