fiskfit

Authors: Maarten L. Buis and Stephen P. Jenkins

fiskfit fits by ML the 2 parameter Fisk (1961) or log-logistic distribution, optionally as dependent on covariates, to sample observations on a random variable var. Unit record data are assumed (rather than grouped data).

This package can be installed by typing in Stata: ssc install fiskfit

Supporting materials

Reference

Fisk, P.R. (1961). The Graduation of Income Distributions. Econometrica 29: 171-185.

Example

. sysuse nlsw88, clear (NLSW, 1988 extract)

. . fiskfit wage, stats

Iteration 0: log likelihood = -6137.2866 Iteration 1: log likelihood = -6135.4711 Iteration 2: log likelihood = -6135.4704 Iteration 3: log likelihood = -6135.4704

ML fit of Fisk distribution Number of obs = 2246 Wald chi2(0) = . Log likelihood = -6135.4704 Prob > chi2 = .

------------------------------------------------------------------------------ | Coef. Std. Err. z P>|z| [95% Conf. Interval] -------------+---------------------------------------------------------------- a | _cons | 3.088234 .0539044 57.29 0.000 2.982583 3.193885 -------------+---------------------------------------------------------------- b | _cons | 6.361959 .0759327 83.78 0.000 6.213133 6.510784 ------------------------------------------------------------------------------ ------------------------------------------------------------ Quantiles Cumulative shares of total wage (Lorenz ordinates) ------------------------------------------------------------ 1% 1.43676 0.00142 5% 2.45199 0.01209 10% 3.12319 0.03055 20% 4.06105 0.07808 25% 4.45753 0.10609 30% 4.83544 0.13663 40% 5.57919 0.20507 Mode 5.11820 50% 6.36196 0.28347 Mean 7.60789 60% 7.25456 0.37279 Std. Dev. 5.84745 70% 8.37038 0.47515 75% 9.08003 0.53241 Variance 34.19270 80% 9.96652 0.59488 Half CV^2 0.29538 90% 12.95937 0.74282 Gini coeff. 0.55381 95% 16.50683 0.83795 p90/p10 4.14941 99% 28.17065 0.94513 p75/p25 2.03701 ------------------------------------------------------------

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