A thermometer can be perfectly accurate and still tell you almost nothing about whether you should go outside. It measures temperature. It doesn’t measure rain, wind, sunlight, or what you’re wearing. The instrument isn’t wrong. The measurement is simply incomplete. Trading data works the same way. Win rate can be accurate. Profit factor can be accurate. Sharpe ratio can be accurate. Yet none of them, alone, tells you what produced the result. Two strategies can have identical returns and completely different underlying behavior. One may depend on a few extraordinary trades. Another may earn small gains consistently and occasionally suffer large losses. Same headline number. Different machine underneath. The danger isn’t bad data. It’s asking good data to answer a question it was never designed to answer. Measurement is not understanding. #Trading# #Statistics# #RiskManagement#