A related issue I seem to be having on Prediction Book. Judging from my past predictions I'm generally underconfident by quite a bit. According to the outcome graph no matter what percentage I estimate for something to happen, as long as I am giving it more than 50%, it seems to happen around 88% of the time. Slightly more for the >90% section, and similarly for the rounding to 100%, so my probability are at least weakly correlated in the right direction. Any thoughts on what I can do to better calibrate myself?
You don't have very many predictions judged, so I'm not sure how reliable your worry is - only 8-11 predictions for each decile seems quite possible to just get lucky. Assuming that's not the case, you could try mechanically bumping up every prediction by 10% and see what happens.
This essay exists as a large section of my page on predictions markets on
gwern.net: http://www.gwern.net/Prediction%20markets#1001-predictionbook-nights