PIP: The Brass-inspired Preceding Birth Technique (PBT), is an indirect estimation technique with low costs of administration. PBT involves asking women at a time close to delivery about the survival of the preceding births. The proportion dead is close to the probability of dying between the birth and the second birthday or an index of early childhood mortality (II or Q). Brass and Macrae have determined that II is an estimate of mortality between birth and an age lower than the birth interval or around 4/5 of the birth interval. Hospital and clinic data are likely to include a concentration of women with lower risks of disease because of higher educational levels and socioeconomic status. A simulation of PBT data from the World Fertility Survey for Mexico and Peru found that the proportions of previously dead children were 0.156 in Peru and 0.092 in Mexican home deliveries. Maternity clinic proportions were 0.088 in Peru and 0.066 in Mexico. Use of clinic and hospital data collection underestimated mortality by 32% in Peru and 15% in Mexico. Another alternative was proposed: interviewing women at some other time than delivery. If the interview was during a child/infant intervention after delivery, the subsample would still be subject to a bias, but this problem could be overcome by computing the weighted average of the actual probability of the older child being dead and the conditional probability of the younger child being dead or both younger and older children being dead. Correction factors could be applied using the general standard of the logit life table system of Brass. Calculation of a simple average of the ages of the younger children could provide enough information to help decide which tables to use. Five surveys were selected for testing the factors of dependence between probabilities of death of successive siblings: Bangladesh, Lesotho, Kenya, Ghana, and Guyana. Higher mortality was related to lower dependency factors between the probabilities of death of successive siblings. Application of the PBT to Mexican data with corrections proved valuable and could be applicable to an immunization campaign or child nutrition program for data collection.^ieng