← All parts of this equation

Equation 24 · Part 1 · Einstein's Random Walk and the Mathematics of Genetic Drift

Symbol p

p=0.5p=0.5
pp

What this part means

the starting from frequency.

Its job in the formula

p is part of the quantity the equation computes from the expression on the right.

Where the article explains it

Kimura’s 1962 formula for the probability that a gene with selective advantage s eventually fixes, starting from frequency p in a population of effective size N , is u(p) = 1−e−4Nsp1−e−4Ns\frac{1-e^{-4Nsp}}{1-e^{-4Ns}} as verified directly from his derivation [ 7 ] .

The passage around this formula

The same second-derivative operator acts on a diffusion term in both; only the variable and the coefficient it multiplies have changed. One honest difference is worth stating rather than smoothing over: Einstein’s D is a constant, fixed once by temperature and viscosity, while Kimura’s V(p) depends on the frequency itself, so the spread is fastest near p=0.5 and vanishes at the boundaries — an allele already fixed or already lost has nothing left to drift into [ 7 ] . The operator is identical; the coefficient it acts on has learned something about the biology.

Read this part in the article →

Learn the underlying idea

A variable is a named place for a value. Its letter is a local label: x can mean position in one formula and a data point in another.

Open the illustrated variables: a letter stands for a value guide →

See this notation across published equations →

Sources cited in the surrounding passage

These citations provide research context; check each source for the exact claim it supports.