Foundations · Methods and evidence
Every Method Works for Someone. None Works Without an Edge and Discipline
Fit makes a process more executable. It cannot make a weak idea profitable. For active decisions, evidence of an edge matters. For indexing, suitable exposure and cost control do a different job.
A method can feel natural and still lose money. You can enjoy research, follow charts carefully, or hold losses without panicking, and still have no reason to expect the result you want.
That is the limit of fit. The Four Levers help identify what a method asks of your life. They do not certify your forecasts, create a mispricing, or pay the costs of trading.
The method is not the result
Value is a lens for price and business worth. Growth examines business expansion. Momentum examines persistent price strength. Charting uses market-generated information. Trading describes an active process over particular holding periods. Income describes a cash-flow objective. Passive indexing is an implementation approach.
These overlap. A growing business can be undervalued. An income portfolio can be indexed. A chart can help define an active position’s invalidation without becoming the reason to own the company. The labels are useful introductions. The real explanation is how the process is supposed to work, what can defeat it, and what it costs.
What counts as an edge?
For an active strategy, an edge is a defensible reason to expect better outcomes than an appropriate alternative after relevant costs and risks. It might be better analysis, better execution, a repeatable signal, or an ability to hold uncertainty that others cannot. Each explanation needs evidence.
A memory of three good trades is weak evidence. So is a backtest assembled after looking at the winning period. A credible claim needs defined rules, appropriate data, a fair comparison, and scrutiny of costs, failed cases and changing conditions.
A method that requires buying before an announcement cannot be tested using information published afterwards. That sounds obvious. It is also how an impressive-looking historical result becomes impossible to reproduce.
Passive investing has a different bargain
A broad index investor does not need a personal stock-picking edge to seek the return of the chosen market. The bargain is exposure to assets, market risk, cost control and discipline. It still requires an appropriate allocation, access to money when needed, and an ability to maintain the policy.
Sharpe’s arithmetic explains why aggregate active management, under his definitions, cannot outperform aggregate passive management after higher costs. That is a constraint on the average. It does not prove that no active investor succeeds, and it does not identify which one will succeed next.
Hypothetical calculation
Across 20 trades, assume ten wins of $150 and ten losses of $100. Gross profit is $500. If total entry-and-exit friction is $30 per completed trade, costs are $600 and the net result is a $100 loss, before tax. A 50 per cent win rate and larger wins than losses did not overcome the cost. This illustration is not evidence of a strategy’s future expectancy.
Discipline is necessary, not magical
Discipline reduces avoidable departures from a sound process. It cannot guarantee that the process is sound. Repeatedly executing a negative-expectancy rule reproduces the problem more consistently.
Good discipline therefore includes a review rule. What evidence would suggest that the original assumptions no longer hold? What record is needed to distinguish a bad run from a deteriorating process? What happens while that question is unresolved? Changing a rule because it lost yesterday is drift. Reviewing it because its assumptions have been invalidated is part of disciplined execution. Record the reason and the timing so the difference is visible later.
What to do with this
Choose one method you use or are considering. Write its expected source of return, its main failure mode, and its costs. Then mark which statement rests on evidence and which remains an assumption.