The Lab Library
Learn
Plain-English guides to reading a bet the way the Lab does. The math the books don’t itemize: correlation, the SGP tax, fair prices, trap legs. Taught for people betting their first season, no stats degree required.
Parlays & Correlation
How Do I Find the Weakest Leg in My Parlay?
Usually it is your longest price: in our graded MLB slips it was the leg that missed 56 times in 100. What cutting it really buys you, and why ET’s own letters got this wrong.
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Betting Basics
Betting Apps That Aren’t Sportsbooks: A Beginner’s Guide to Betting Tools
A sportsbook takes your bet. Everything else helps you understand it. Seven kinds of betting apps, what each can and cannot tell you, which one you need first, and three questions to ask before you pay.
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Model Honesty
Are Betting Prediction Apps Accurate? We Graded 73,272 of Ours
On our MLB board, home run reads said about 34% on average and 19 in 100 homered. Every read we graded, where our numbers ran high, what we changed on September 10, and three questions to ask any prediction app.
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NFL
Why NFL Week 1 and 2 Player Props Are Unreliable
Every Week 1 projection is mostly about last season, because this season has produced nothing to project from. What we measured when we tried to fix that, and why we withhold most of our own NFL board until the sample arrives.
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Parlays & Correlation
Why Do Parlays Always Lose? The Vig Stacks on Every Leg
The house edge compounds instead of averaging: 4.5% on one bet, about 21% on a five-leg. The toll ladder, thirty years of Nevada hold data, and the two things that make a parlay defensible.
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Parlays & Correlation
Why Did My Parlay Lose on One Leg? The Math Nobody Shows You
Going 4-1 pays the same as going 0-5: nothing. Why the near-miss is the most common outcome of a good ticket, and how the house edge stacks with every leg you add.
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Betting Basics
What Is a Parlay? How Multi-Leg Bets Actually Work
One ticket, multiple legs: the odds multiply and every leg must win. How the payout is built, what a push does, and the three kinds of parlay you’ll actually meet.
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Betting Basics
How to Read American Odds: What +150 and −110 Actually Mean
Minus is what you risk, plus is what you win. The two formulas that turn any price into a probability — and why both sides of a coin flip cost −110.
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Parlays & Correlation
How Much Does a Parlay Pay? The Payout Chart for 2 to 12 Legs, With the Math
A 2-leg at −110 pays +264, a 5-leg +2436, a 10-leg +64208. The chart through 12 legs with $50 and $100 examples, the fair odds beside each, push rules, the payout cap, and what the sportsbook keeps.
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Variance & Discipline
Is a Losing Streak Normal in Sports Betting?
A 55% bettor has a 91% chance of losing four in a row inside 100 bets. Why your record is not evidence yet, how many bets it would take to be, and the three things worth watching instead.
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Odds & Prices
What Is Line Shopping? Why the Same Bet Pays Different Odds at Different Sportsbooks
The same wager pays +200 at one book and +250 at another. Why odds differ, what shopping is worth over a season, and how to tell a real gap from a stale line.
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Parlays & Correlation
Is My Parlay Good? How to Tell Before You Bet
The 4-step pre-bet checklist: standalone leg value, correlation, payout math, and trap legs. Run it on any slip before the money leaves your account.
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Parlays & Correlation
What Is the SGP Tax? The Correlation Tax on Same-Game Parlays, Explained
The gap between what your parlay would pay if the legs were independent and what the book quotes, with the napkin math worked out step by step.
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Parlays & Correlation
Same-Game Parlay Correlation: Why Your SGP Quietly Loses (and How to Spot It)
Positive vs. negative correlation, the 15–25% hidden hold on SGPs, and how to spot legs that move together before you lock them.
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ET Parlays is sports-analytics research and decision-support, not a sportsbook, and never a promise of a winning bet. New guides land as they’re written. How we grade ourselves, and every place our numbers are currently wrong, is on the methodology page. What each prop market costs to bet, measured across every price we have captured, is in the Parlay Tax Index.