Modelling memory in coal tits: an illustration of the EM algorithm

Some species of birds are known to use memory to retrieve previously stored food. A series of experiments on one of those species, coal tits, investigated various aspects of such memory. For one particular experiment, a number of statistical models describing the memory were fitted. However, some of the data were unavoidably incomplete. The expectation maximization (EM) algorithm provides a means of incorporating the incomplete data into the fitting procedure.