© 1976 by Biometrika Trust
On the extermal quotient from a gamma sample
Department of Statistics, Tel-Aviv University Israel
The extremad quotient, Q, is defined for nonnegative observations as the ratio of the largest observation in a sample to the smallest observation. This paper gives the exact distribution of this quotient based on a sample drawn from a gamma distribution. The statistic is scale-free, and its distribution depends only on the sample size n and on the shape parameter
of the underlying gamma distribution. Applications include certain areas of industrial quality control and Hartley's maximum F ratio, Fmax for testing heterogeneity of variances in a multisample, equal degree of freedom situation. The kth moment of Q exists only if k <
the first and second moments are evaluated for various values of n and
. Comparisons are made with David's tables of the percentage points of Fmax.
Key Words: Extremal quotient Gamma distribution Maximum F ratio