What's causing P2Pool's bad luck? While looking at the current pool luck chart on p2pool.info, I noticed that the pool as a whole seems to slowly deviate from the predicted rate of finding blocks.



From the other chart it appears that it is consistently underperforming as of 3 weeks ago.



Is there a good reason or is it just a fluke in the probabilities of finding a block?
This looks like plain old bad luck.

P2pool is a small pool and 3 weeks is a short time. With current hashpower at pools this is like measuring BTCGuild for less than 12 hours. BTCGuild can have bad luck for 12 hours, and P2pool can have bad luck for 3 weeks.

That said, all pools underperform on average when compared to a simple expected income. That's because of orphaned blocks, typically 1 to 2 percent. And if you count stale/rejected shares in the hashrate, then it will underperform even more. But if income from transaction fees is not included in that expected average, then that may even out the orphans and stale work.