A method is presented of producing a multi-way analysis or account of the variance of the relative change in density from one year to the next of a wild population which is structured in some way (e.g. by age group). The method is dependent on accounting identities in which the relative change in size of the whole population is expressed as a sum over age (or other) groups of recruitment and mortality components, which are each expressed in terms of products of factors such as birth rate, and offspring and adult survival rates. The account consists of terms due to (a) variation within and covariation between subgroups (e.g. age groups), (b) variation in recruitment and adult mortality, and the covariation between them, and (c) variation in and covariation between the factors