These parameters (q t,a t) are allowed to change with every time step of the random walk. By this way, heterogeneous time series of arbitrary complexity can be described ( Supplementary Note 2 ).

Random Walk with Drift (Y t = α + Y t-1 + ε t) If the random walk model predicts that the value at time "t" will equal the last period's value plus a constant, or drift (α), and a white noise ...

This paper addresses a key puzzle in international finance: whether exchange rates follow a random walk or exhibit predictable patterns. We demonstrate that exchange rates can possess a unit root ...