 This formula tells us, for each possible value of \(X(t+1)\), what its probability is as a function of the population size \(N\) and the allele’s frequency in the parental generation \(p(t).\) From this, we can easily compute the expected value of \(X(t+1)\), denoted \(E(X(t + 1))\), which turns out to simply be equal to \(X(t)\). This is quite intuitive: since the second generation is formed by random sampling, the number of copies of the allele is just as likely to increase as to decrease, so the expected number of copies in generation \(t+1\) equals the actual number of copies in generation \(t.\) It follows that the expected change in allele frequency from generation \(t\) to \(t+1,\) denoted \(E(\Delta p)\), is equal to zero.