How do you verify a trading claim you read online?

"This indicator has a 90% win rate" — every claim needs the same questions: over what sample, after what costs, with what rules, survivorship included? Asking them is a skill traders develop slowly.

What's your checklist?

• the questions you ask of any claim
• the claim you once believed and later debunked
• how you test claims cheaply before trusting them

The expectancy guide supplies the debunking maths.