I was reading through a paper titled: "Estimating Safety by the Empircal Bayes Method: A Tutorial" found online at: http://www.oocities.org/hauer@rogers.co ... Bpaper.pdf. The equation for calculating the weighted adjustment is different than that given in the HSM Appendix A for Part C (Equation A-5, Page A-19, Volume 2). In the paper, the calculation for the weighting factor (equation 2 on page 5 of the paper) includes a term that divides the predicted crash frequency by the overdispersion parameter whereas in the HSM equation the same term multiplies the predicted crash frequency by the overdispersion parameter. Can anyone shed some light on why there is a difference between the two equations? Is one right and the other wrong? Do they simply represent two different weighting methodologies? Or am I just completely confused as to what is going on?

Thanks in advance.