Assessing and Improving Stationarity
In essence, the stationarity of a time series (such as market price changes, indicators, or individual trade returns) refers to the degree to which its statistical properties remain constant over time. Statisticians may cringe at such a loose definition, but that captures the practical meaning of the term. When we use market history to create a (preferably) profitable trading system, we are implicitly counting on the historical patterns that produced backtesting profitability to remain in force for at least the near-term future. ...
