1. A method for calculating by a computer a quantile estimate of a data stream, comprising the steps of: calculating a first quantile estimate based at least in part on a first sample quantile calculated from a first observation sample; calculating a first standard deviation estimate based at least in part on a first sample standard deviation calculated from the first observation sample; calculating a second sample standard deviation from a second observation sample; calculating a second standard deviation estimate based at least in part on the first standard deviation estimate and the second sample standard deviation; calculating a first update increment based at least in part on the second observation sample and based at least in part on the product of the second standard deviation estimate times a first value of a log odds ratio function; and calculating a second quantile estimate as the sum of the first quantile estimate plus the first update increment.