As forex traders, we define our edge as something we have seen in the market. This event has repeated frequently enough for us to think we can develop a trading strategy around it.
Backtesting starts with gathering as much data as possible.We cannot assess the relative merits of an edge by looking at the results of just one past trade.
The results from our backtesting are encouraging so we move into the testing on live data. This stage is called the forward testing stage and is where we apply our strategy and its rules to new live data.