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Approximations to the characteristic function of the lognormal distribution are computed and used to calculate approximations to theden/sity of sums of lognormal random variables.

A binary logit model is adapted to the spatial point process represented by outcomes of wildcat wells as a function of drilling history. The probability of success of the (n + 1) st wildcat is made dependent on this well's location and on outcomes of wildcats previously drilled within a distance d of this well. This simple model is a device for investigating patterns of dependencies of wildcat well outcomes and for projecting probabilities of drilling success at particular locations. Application to two Canadian petroleum plays show how to use it.

SUMMARYUnder the assumption that neither the mean vector nor the variancecovariance matrix are known with certainty, the natural conjugate family of prior densities for the multivariate Normal process is identified.Prior-posterior and preposterior analysis is done assuming that the prior is in the natural conjugate family. A procedure is presented for obtaining non-degenerate joint posterior and preposterior distributions of all parameters even when the number of objective sample observations is less than the number of parameters of the process.

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