Glossary

Key terms and concepts used throughout EVSignals, including sports betting, prediction markets, and market mechanics.

Expected Value & Probability Odds & Lines Market Types & Analysis Prediction Markets Bankroll Management API & Technical Terms Market Mechanics Crypto & DeFi Prediction Markets Platform-Specific Terms Advanced Strategies Regulatory & Legal

Expected Value & Probability

Expected Value (EV)

The average amount you can expect to win or lose per bet if you were to place the same bet many times. Calculated as: (Probability of Winning × Potential Profit) - (Probability of Losing × Stake). A positive EV (+EV) indicates a profitable bet over time.

Example: If a bet has +5% EV, you can expect to profit $5 for every $100 wagered over the long run.

+EV (Positive Expected Value)

A bet where the expected value is greater than zero, meaning the true probability of winning is higher than what the odds imply. These are the opportunities EVSignals identifies.

Example: A coin flip at 2.10 odds (implied 47.6% probability) when the true probability is 50% would be +EV.

-EV (Negative Expected Value)

A bet where the expected value is less than zero. Most bets offered by sportsbooks are -EV due to the built-in margin (vig/juice).

Example: Standard -110 odds on both sides of a spread creates -EV for bettors.

Edge

The percentage advantage you have over the sportsbook. Synonymous with +EV percentage. An edge is created when you can identify the true probability more accurately than the market.

Example: A 3% edge means you have a 3% expected return on investment.

Fair Odds

The odds that would result in zero expected value - where the implied probability exactly matches the true probability. Also called 'true odds' or 'no-vig odds'.

Example: If the true probability is 50%, fair odds would be 2.00 (even money).

Implied Probability

The probability of an outcome as suggested by the betting odds. Calculated as 1 / decimal odds. Does not account for the bookmaker's margin.

Example: Odds of 2.50 imply a 40% probability (1 / 2.50 = 0.40).

True Probability

The actual likelihood of an outcome occurring, as estimated by models or analysis. When true probability differs from implied probability, an edge exists.

Example: A model might estimate a team's true win probability at 55% while the market implies only 48%.

Kelly Criterion

A formula for determining the optimal bet size based on your edge and bankroll. It maximizes long-term growth while minimizing risk of ruin. Formula: (bp - q) / b, where b = decimal odds - 1, p = probability of winning, q = probability of losing.

Example: With a 5% edge at 2.00 odds, Kelly suggests betting 5% of your bankroll.

Odds & Lines

Decimal Odds

The most common odds format globally. Represents the total return (including stake) for a winning bet. Used throughout the EVSignals API.

Example: Odds of 2.50 mean a $100 bet returns $250 ($150 profit + $100 stake).

American Odds

Odds format common in the US. Positive odds (+150) show profit on a $100 bet. Negative odds (-150) show the stake needed to profit $100.

Example: +200 = 3.00 decimal. -150 = 1.67 decimal.

Moneyline (ML)

A bet on which team will win outright, with no point spread involved. The favorite has lower payout odds while the underdog has higher odds.

Example: Chiefs -150 vs Ravens +130 - bet on either team to win.

Spread / Point Spread

A handicap applied to level the playing field between teams. The favorite must win by more than the spread; the underdog can lose by less than the spread or win outright.

Example: Chiefs -3.5 means they must win by 4+ points to cover.

Total / Over-Under

A bet on whether the combined score of both teams will be over or under a specified number.

Example: Over 48.5 means you're betting the total score exceeds 48 points.

Vig / Juice / Margin

The bookmaker's commission built into the odds. It's why both sides of a bet typically have negative EV. Standard vig is around 4.5% (both sides at -110).

Example: -110/-110 pricing means the book takes ~4.5% regardless of outcome.

Line Movement

Changes in odds or spread over time, usually due to betting action or new information. Sharp bettors often cause significant line moves.

Example: The spread moving from -3 to -4.5 indicates heavy action on the favorite.

Opening Line

The initial odds or spread set by bookmakers when a market first opens. Often considered the 'sharpest' line before public betting influences it.

Example: The game opened at Chiefs -2.5 before moving to -3.5.

Closing Line Value (CLV)

The difference between the odds you bet and the final odds at close. Consistently beating the closing line is the best indicator of long-term profitability.

Example: Betting at +150 when the line closes at +120 shows positive CLV.

Market Types & Analysis

Sharp

A sophisticated bettor or betting syndicate known for winning consistently. Sharps move lines and are tracked closely by bookmakers.

Example: Sharp action on the underdog might indicate value that the public is missing.

Square / Public

Casual bettors who tend to bet with emotion, on favorites, and on popular teams. Their betting patterns are often predictable.

Example: The public heavily backs the Cowboys in prime-time games.

Steam Move

Rapid, significant line movement caused by heavy sharp action across multiple sportsbooks simultaneously. Often indicates strong conviction from professional bettors.

Example: A steam move on the under might signal information about a key player's injury.

Reverse Line Movement (RLM)

When the line moves in the opposite direction of the majority of bets. This typically indicates sharp money on the less popular side.

Example: 70% of bets on Team A, but the line moves toward Team B = RLM.

Arbitrage (Arb)

A risk-free profit opportunity created when odds discrepancies between sportsbooks allow betting on all outcomes for guaranteed profit. Rare and quickly corrected.

Example: Book A has Team X at +110, Book B has Team Y at +110 = arb opportunity.

Middling

A strategy where you bet both sides of a game at different point spreads, hoping the final score lands between them for a double win.

Example: Bet Chiefs -3 early, then Ravens +6 later. If Chiefs win by 4-5, both bets win.

Hedging

Placing a bet on the opposite side of a previous bet to guarantee profit or minimize losses, often used with futures or parlays.

Example: You bet Chiefs to win the Super Bowl at +1500. Hedge with the opponent in the final game.

Prediction Markets

Prediction Market

A market where participants trade contracts based on the outcome of future events. Prices reflect the crowd's probability estimates. Examples include Polymarket and Kalshi.

Example: A contract trading at $0.65 implies a 65% probability of that outcome.

Kalshi

A CFTC-regulated prediction market in the US offering contracts on economic, political, and other events. EVSignals scans Kalshi for +EV opportunities.

Example: Trade 'Will the Fed raise rates in January?' with real money on Kalshi.

Polymarket

A decentralized prediction market using cryptocurrency. Offers markets on politics, sports, crypto, and current events globally.

Example: Political election markets often have higher volume on Polymarket.

A tradeable unit in a prediction market that pays $1 if the outcome occurs and $0 otherwise. Buy low, sell high, or hold to resolution.

Example: Buy a 'Yes' contract at $0.45, sells for $1.00 if the event happens.

Bankroll Management

Bankroll

The total amount of money you have dedicated to betting. Proper bankroll management is crucial for long-term success.

Example: With a $10,000 bankroll and 1% bet sizing, each wager is $100.

Unit

A standardized bet size, typically 1-2% of your total bankroll. Using units allows consistent comparison regardless of bankroll size.

Example: A 2-unit bet with a $5,000 bankroll = $100 (at 1% per unit).

ROI (Return on Investment)

The profit or loss expressed as a percentage of total amount wagered. A key metric for evaluating betting performance.

Example: Winning $500 on $10,000 in total bets = 5% ROI.

Variance

The natural fluctuation in results due to randomness, even when making +EV bets. Short-term results can differ significantly from expected value.

Example: Going 3-7 on +EV bets is possible due to variance, even with an edge.

Risk of Ruin

The probability of losing your entire bankroll. Proper bet sizing and bankroll management minimize this risk.

Example: Betting 50% of your bankroll per bet dramatically increases risk of ruin.

Drawdown

A peak-to-trough decline in bankroll value during a losing streak. Maximum drawdown is an important risk metric.

Example: A 20% drawdown means your bankroll dropped from $10,000 to $8,000.

API & Technical Terms

API Key

A unique identifier used to authenticate your requests to the EVSignals API. Keep your API keys secret and never share them publicly.

Example: evs_live_abc123... is used in the Authorization header.

Rate Limit

The maximum number of API requests allowed per time period. Exceeding limits results in 429 errors. Check X-RateLimit-* headers.

Example: Professional tier allows 1,000 requests per minute.

Webhook

A URL that receives real-time notifications when events occur. Webhooks push data to you instead of requiring you to poll the API.

Example: Receive instant alerts when new +EV signals are detected.

WebSocket

A persistent connection that streams real-time data. More efficient than polling for high-frequency updates like live odds.

Example: Connect to wss://stream.evsignals.com for live odds feeds.

Backtest

Testing a betting strategy against historical data to evaluate its performance. Essential for validating strategies before using real money.

Example: Backtesting showed a 7% ROI over 3 years of NFL data.

Market Mechanics

Order Book

A list of open buy and sell orders for a contract, organized by price. The depth of the order book indicates liquidity and how easily you can enter or exit a position.

Example: The order book shows 500 Yes contracts bid at $0.62 and 300 offered at $0.64.

Liquidity

How easily you can buy or sell a contract without significantly moving the price. Higher liquidity means tighter spreads and less slippage.

Example: Presidential election markets on Polymarket have deep liquidity; niche weather markets may not.

Spread (Bid-Ask)

The difference between the best bid and best ask price for a contract. Tighter spreads indicate higher liquidity and lower trading costs.

Example: A contract with a $0.62 bid and $0.64 ask has a 2-cent spread.

Resolution / Settlement

The process of determining the outcome of a prediction market event and paying out contracts. Yes contracts pay $1, No contracts pay $0.

Example: The 'Will the Fed raise rates?' market resolved Yes, paying $1 to all Yes holders.

CFTC

The Commodity Futures Trading Commission — the US regulatory body that oversees prediction markets like Kalshi. CFTC regulation provides legal certainty for US traders.

Example: Kalshi is CFTC-regulated, while Polymarket operates as a decentralized platform.

Slippage

The difference between the expected price and the actual execution price. Common in low-liquidity markets or with large order sizes.

Example: You expected to buy at $0.55 but got filled at $0.57 due to slippage.

Volume

The total number of contracts traded in a given period. Higher volume generally indicates more interest and better liquidity in a market.

Example: The election market traded $2.4M in volume over the past 24 hours.

Open Interest

The total number of outstanding contracts that have not been settled. Rising open interest with rising prices signals growing conviction.

Example: Open interest in the Fed rate market increased from 50K to 80K contracts ahead of the meeting.

Crypto & DeFi Prediction Markets

USDC Betting

Placing bets using USDC (USD Coin), a stablecoin pegged 1:1 to the US dollar. Polymarket uses USDC on the Polygon blockchain for all trades, providing dollar-denominated betting without traditional banking.

Example: Deposit USDC to your Polymarket wallet to start trading prediction market contracts.

On-Chain Prediction Market

A prediction market that operates on a blockchain, with trades recorded as on-chain transactions. Provides transparency and censorship resistance but may have higher latency than centralized alternatives.

Example: Polymarket runs on Polygon, making all trades publicly verifiable on-chain.

Decentralized Betting

Wagering through decentralized protocols without a central authority controlling funds or outcomes. Smart contracts hold funds in escrow and automatically settle based on oracle-reported outcomes.

Example: Azuro protocol enables decentralized sports betting with liquidity pools and automated market making.

Crypto Sports Betting

Sports betting using cryptocurrency as the medium of exchange. Combines traditional sports wagering with crypto payment rails for faster deposits, withdrawals, and global access.

Example: Bet on NBA games using USDC on Polymarket or through decentralized protocols like Azuro.

Oracle (Prediction Markets)

A system that reports real-world outcomes to smart contracts for market resolution. Prediction markets depend on reliable oracles — Polymarket uses UMA's optimistic oracle, which allows anyone to dispute outcomes.

Example: When an election concludes, the oracle reports the winner so prediction market contracts can settle.

Platform-Specific Terms

Kalshi Fees

Kalshi charges fees on profitable trades, typically around 2% of profit. There are no fees on losing trades. Fee structure may vary by contract type and trading volume.

Example: If you profit $100 on a Kalshi trade, you pay approximately $2 in fees.

Polymarket Deposit

To trade on Polymarket, you deposit USDC to a Polygon wallet. Deposits can be made via crypto exchanges or direct wallet transfers. No minimum deposit required.

Example: Transfer USDC from Coinbase to your Polymarket wallet to start trading.

PredictIt Withdrawal

PredictIt allows withdrawals via bank transfer, typically processed within 5-7 business days. PredictIt charges a 5% fee on all profits when withdrawing, making it one of the most expensive platforms for profitable traders.

Example: A $200 profit on PredictIt results in a $10 withdrawal fee (5%).

Event Contract

A regulated financial instrument that pays out based on the outcome of a specified event. Kalshi offers CFTC-regulated event contracts on economics, politics, climate, and more.

Example: An event contract on 'Will CPI exceed 3% in March?' pays $1 if yes, $0 if no.

Advanced Strategies

Matched Betting

A technique using free bet promotions and back/lay bets to guarantee profit regardless of outcome. Common with sportsbook sign-up offers. Requires accounts on multiple platforms.

Example: Use a $100 free bet on DraftKings and lay the same outcome on Betfair to lock in ~$70 profit.

Value Betting

Identifying and wagering on outcomes where the odds offered are higher than the true probability suggests. The core of profitable +EV trading. Requires accurate probability estimation.

Example: If your model gives a team a 55% chance but odds imply only 45%, that's a value bet.

Model-Based Betting

Using statistical or machine learning models to estimate true probabilities, then comparing those estimates to market prices to find edges. The most systematic approach to +EV betting.

Example: A Poisson regression model for soccer predicts goal totals, which are compared against sportsbook over/under lines.

Elo Rating

A rating system originally designed for chess that assigns numerical ratings to competitors based on win/loss records. Widely adapted for sports prediction models to estimate relative team/player strength.

Example: An Elo model rates Team A at 1650 and Team B at 1520, implying a 68% win probability for Team A.

Poisson Model

A statistical model using the Poisson distribution to predict the number of events (typically goals or points) in a match. Commonly used in soccer and hockey betting to derive fair odds for totals and correct scores.

Example: A Poisson model predicting 1.5 expected goals for Team A and 1.1 for Team B can generate fair odds for any scoreline.

Correlation (Parlays)

When two or more outcomes in a parlay are statistically linked, so one occurring makes the other more likely. Correlated parlays can be +EV when sportsbooks price legs independently.

Example: Betting the favorite to win AND the over is correlated — blowout wins tend to be high-scoring.

Didn't find what you're looking for?

If there's a term you'd like us to add to this glossary, let us know!

Suggest a term