How to Test a Trading Strategy Built From Plain English Rules

A trading idea written in plain English is only useful once it is precise enough to test. "Buy when the stock looks cheap" cannot be backtested. "Buy when the 14 day RSI closes below 30 and sell when it closes above 50" can.

Step 1: Write the rule so a machine can read it

Every strategy needs a universe (which assets), signals (what triggers an entry), an exit, position sizing, and assumed costs. If any of these is missing, the backtest will fill the gap with a default you did not choose.

Step 2: Include costs and slippage

A strategy that trades often can look profitable until commissions, spreads and slippage are counted. Put realistic values into the test before you look at the equity curve.

Step 3: Compare against buy and hold

If a simple buy and hold of the same asset did as well or better over the same period, the strategy needs a clear reason to exist. Nvestiq's backtest report flags this directly, so you can see it without doing the arithmetic yourself.

Step 4: Test across more than one period

A rule that only works in one market regime is a fit to that period. Test a rising stretch, a falling stretch and a sideways stretch, and be suspicious if all the profit comes from one of them.

Step 5: Nudge the settings

If the result depends on one exact parameter value, it is probably curve fit. Check whether the result holds when the thresholds move a little. Our overfitting explainer covers this in more depth.

Step 6: Paper trade before real money

A backtest assumes perfect fills on historical data. Paper trading tests your order types, fills and data feed. Track the gap between expected and actual fill prices from the first day.

Nvestiq runs the same compiled strategy in backtest and in paper trading, so nothing is rewritten between steps. The product is in early access. Nvestiq publishes this page, so weigh it accordingly.