Methods, systems, and apparatus, including medium-encoded computer program products, for analyzing data include: receiving data including responses, and lack thereof, for items of a cognitive test including multiple item-recall trials; processing the data using a stochastic model of a cognitive process, in which a conditional probability distribution of future states of the cognitive process depend upon a present state; and encoding a result of the processing on a non-transitory computer-readable medium for use in an assessment related to cognition; wherein the processing using the stochastic model includes representing recall or recognition of an item in the multiple item-recall trials using distinct cognitive states; and wherein the processing using the stochastic model includes adjusting separate memory storage and retrieval parameters for each of the distinct cognitive states in the modeled cognitive process to account for position of the items in each respective trial of the multiple item-recall trials.