IMF Working Paper 16/172. Kozlowski, J., L. Veldkamp, V. Venkateswaran (2016): The tail that wags the economy: The origin of secular stagnation. VoxEU, 11 September 2016. 5/5  BIS central bankers' speeches
There used to be some elements of predictability for the Australian dollar in that its broad movements could usually be explained by changes in our terms of trade (or its close relative, commodity prices) and the difference between domestic and foreign interest rates. The relationship was not close on a month-to-month or quarter-to-quarter basis, but it could explain the large swings.