Paper 2, Section II, J

Principles of Statistics
Part II, 2010

Define the Kolmogorov-Smirnov statistic for testing the null hypothesis that real random variables X1,,XnX_{1}, \ldots, X_{n} are independently and identically distributed with specified continuous, strictly increasing distribution function FF, and show that its null distribution does not depend on FF.

A composite hypothesis H0H_{0} specifies that, when the unknown positive parameter Θ\Theta takes value θ\theta, the random variables X1,,XnX_{1}, \ldots, X_{n} arise independently from the uniform distribution U[0,θ]\mathrm{U}[0, \theta]. Letting J:=argmax1inXiJ:=\arg \max _{1 \leqslant i \leqslant n} X_{i}, show that, under H0H_{0}, the statistic (J,XJ)\left(J, X_{J}\right) is sufficient for Θ\Theta. Show further that, given {J=j,Xj=ξ}\left\{J=j, X_{j}=\xi\right\}, the random variables (Xi:ij)\left(X_{i}: i \neq j\right) are independent and have the U[0,ξ]\mathrm{U}[0, \xi] distribution. How might you apply the Kolmogorov-Smirnov test to test the hypothesis H0H_{0} ?