1. A method for determining decision metrics in a detector for a memory device, the method comprising: receiving a plurality of signal samples; extracting a set of statistics from the signal samples, wherein at least one of the statistics is non-linear or complex, is derived from a plurality of the signal samples, and is not a function of at least one real linear statistic that is derived from a plurality of the signal samples; and applying at least one decision metric function to the set of statistics to determine at least one decision metric value corresponding to at least one postulated symbol.