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Gibrat's Distribution

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GibratsDistribution

Gibrat's distribution is a continuous distribution in which the logarithm of a variable x has a normal distribution,

P(x)=1/(xsqrt(2pi))e^(-(lnx)^2/2),
(1)

defined over the interval [0,infty). It is a special case of the log normal distribution

P(x)=1/(Sxsqrt(2pi))e^(-(lnx-M)^2/(2S^2))
(2)

with S=1 and M=0, and so has distribution function

D(x)=1/2[1+erf((lnx)/(sqrt(2)))].
(3)

The mean, variance, skewness, and kurtosis excess are then given by

mu=sqrt(e)
(4)
sigma^2=e(e-1)
(5)
gamma_1=(e+2)sqrt(e-1)
(6)
gamma_2=e^4+2e^3+3e^2-3.
(7)

See also

Log Normal Distribution

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References

Gibrat, R. Les Inégalités économiques. Paris: Recueil Sirey, 1931.Mansfield, E. "Entry, Gibrat's Law, Innovation, and the Growth of Firms." Amer. Econ. Rev. 52, 1023-1051, 1962.

Referenced on Wolfram|Alpha

Gibrat's Distribution

Cite this as:

Weisstein, Eric W. "Gibrat's Distribution." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/GibratsDistribution.html

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