Picture 1,024 people each flipping ten coins and calling heads a win. Someone will probably post a perfect record. That is selection bias betting in miniature, and it is why a great-looking streak can mean nothing. You will learn how survivorship bias hides forecasters who quit after bad runs, how look-ahead bias sneaks in facts nobody had at post time, and how multiple testing manufactures impressive records by chance alone. A red-flag list covers things like last ten winners with no full record, profit shown without total stakes, edited picks and unreported pushes. Then you will set up a forward test so a record gets judged on picks made after the rules were fixed.
Learning objectives
- Distinguish observed public content from independently verifiable records.
- Reconstruct calculations and identify common data-quality traps.
- Apply procedures to paper-only examples and document uncertainty.
