Betting Concepts, Explained
Plain-English explainers for the ideas behind the numbers — what a parlay is, how odds and vig work, what a hit rate really measures, and why same-game legs move together. From an analytics tool, not a sportsbook: we explain how to read a number, never which bet to make.
Featured guide
Same Game Parlay (SGP) Guide
What an SGP is, why same-game legs move together, and how a book prices that correlation.
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What Is a Parlay?
The plain-English basics: what a parlay is, why every leg must win, and the payout trade-off.
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How to Read American Odds
How lines like +150 and -110 translate into implied probability and payout.
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Parlay math
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How Do Parlay Odds Work?
Why parlay payouts multiply rather than add, and how fast the odds stack as you add legs.
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Does Adding Legs Lower Your Odds?
Each extra leg raises the potential payout but lowers your chance of cashing — here is the math.
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What Is Vig in Betting?
The margin a book builds into its odds, where it hides, and how we strip it back out.
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Why Did My Parlay Lose?
Why a parlay can lose even when most of its legs hit — variance by design, not bad luck.
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Reading the data
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What Is a Hit Rate in Betting?
What a hit rate measures, and how to read one without over-reading a small sample.
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Hit-Rate Windows: Last 7, 15, 30 & Season
Why we show four windows, and what each one tells you about recent versus baseline form.
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Correlation in Betting, Explained
How positive and negative correlation link outcomes that share a single game.
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WNBA Player Props, Explained
How WNBA player-prop markets work and how to read the hit-rate data behind them.
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Bettorly is an analytics tool — we don’t take bets and don’t sell picks. Historical frequencies never guarantee a future result. 21+. Gambling problem? Call or text 1-800-GAMBLER.
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