 Random drift greatly complicates the task of the population geneticist. For in the presence of drift, it is no longer possible to deduce the genetic composition of the population in generation \(t+1\) from its composition in generation \(t\); so no recurrence relation for an allele’s frequency, of the sort expressed in equation (1) above, can be derived. Instead, the aim must be to deduce the probability distribution over all the possible genetic compositions of the population in generation \(t+1\). From this, it is sometimes possible to extract a prediction about the long-term fate of an allele.