Improved Sequential Stopping Rule for Monte Carlo Simulation
  This paper presents an improved result on the negative-binomial Monte Carlo technique analyzed in a previous paper for the estimation of an unknown probability p. Specifically, the confidence level associated to a relative interval [p/\mu_2, p\mu_1], with \mu_1, \mu_2 > 1, is proved to exceed its asymptotic value for a broader range of intervals than that given in the referred paper, and for any value of p. This extends the applicability of the estimator, relaxing the conditions that guarantee a given confidence level. 
Luis Mendo and Jose M. Hernando