Exact Non-Parametric Tests for a Random Walk with Unknown Drift under Conditional Heteroscedasticity Staff Working Paper 2001-2 Richard Luger This paper proposes a class of linear signed rank statistics to test for a random walk with unknown drift in the presence of arbitrary forms of conditional heteroscedasticity. Content Type(s): Staff research, Staff working papers Topic(s): Econometric and statistical methods JEL Code(s): C, C1, C12, C2, C22