Odds Boost Labels Raise Bet Size 24%, Not Win Rate
Sportsbook customers shown a boosted-odds badge on a moneyline bet staked 24.1% more on average than customers shown the identical line without the badge, according to a controlled experiment run across three U.S.-licensed operators in the fourth quarter of 2025. The same study found no statistically significant difference in the rate at which those bets won: 47.9% with the badge versus 48.2% without it, a gap well inside the margin of error for the sample. In other words, the label moved money, not math.
That finding lands at an awkward moment for an industry that has spent four years building promotional infrastructure around the word "boost." The label is now standard furniture on sportsbook apps — a small flame icon, a lime-green percentage, a strikethrough on the old price — and it is deployed on markets where the underlying probability hasn't changed at all. What the experiment suggests is that the badge functions less as a price signal than as a behavioral one, and that the two have quietly decoupled.
What the experiment actually measured
The study, conducted by a research group affiliated with a Mid-Atlantic university's behavioral economics lab and shared with several state gaming regulators before publication, enrolled 11,400 bettors who had placed at least one wager in the prior 90 days. Participants were randomly assigned to one of two app interfaces for a four-week window ending December 19, 2025. The control group saw standard American odds with no promotional styling. The treatment group saw the same odds rendered with a "Boosted" pill, a strikethrough on the prior price, and a small arrow icon — but the actual price was identical between groups on every market tested.
That last detail matters. This wasn't a study of whether genuinely better odds attract more money. It was a study of whether the appearance of better odds does, independent of the number. Across 41,000 tracked wagers, the treatment group's mean stake was $34.60 versus $27.88 in the control — the 24.1% figure. Median stake moved less dramatically, from $20 to $25, which tells you the effect was concentrated in a subset of users rather than spread evenly.
The win-rate comparison is the part operators will read twice. Treatment-group bets won 47.9% of the time; control-group bets won 48.2%. The confidence interval on that difference spans zero comfortably. If the boost label had any effect on which bets people selected — and the study's authors believe it did, based on a secondary analysis of market selection — it did not translate into better outcomes. Bettors in the treatment group gravitated slightly toward longer-odds markets (parlays and same-game combinations), but the shift was modest and the aggregate hold was nearly identical between cohorts: 6.8% versus 6.7%.
"The label is doing work, but not the work it claims to do," said Dr. Renata Alvarez, the lab's lead investigator, in a call discussing the findings. "It's not improving the price. It's not improving the outcome. It's improving the amount wagered. Those are three different things and the industry has been allowed to blur them."
Why the strikethrough is the active ingredient
The study's design included a third arm, dropped from the headline numbers because of a smaller sample, that tested the badge and the strikethrough separately. Early results, per Alvarez, suggest the strikethrough — the crossed-out old price — is responsible for most of the stake inflation, while the "Boosted" text alone moved bet volume only marginally. That's consistent with a well-documented retail phenomenon: anchor pricing. When a shopper sees $45 crossed out and $40 beside it, the brain processes the second number as a gain relative to the first, regardless of whether $40 was ever a real market price.
In sportsbook terms, the "old" price in a boosted-odds display is frequently not a price anyone could have bet. It's often a rounded reference number or the operator's own theoretical fair line. Several state regulators have looked at this and concluded it isn't technically deceptive, because the displayed current odds are accurate. The experiment suggests that legal standard may be answering the wrong question.
The regulatory gap nobody has closed
As of March 2026, 38 states plus the District of Columbia permit some form of online sports betting. Of those, roughly a dozen have rules that specifically address promotional odds displays, and the language varies enough to be nearly useless as a national baseline. Massachusetts requires that boosted odds be "clearly identified as a temporary promotion," which the badge satisfies. Ohio's rules prohibit advertising that "misrepresents the likelihood of winning," which is arguably satisfied too, since the badge doesn't state a likelihood at all.
The gap is structural. Regulators write rules about what an ad says. The boost badge doesn't say much. It implies.
"There's no false statement anywhere in a boosted-odds label," said Marcus Deane, a former deputy director at a state gaming division who now consults for compliance vendors. "That's the whole problem. You can't cite a violation because there's no claim to falsify. The claim is ambient."
Deane points to a comparison regulators have used internally: grocery store "was $4.99, now $3.99" tags, which the Federal Trade Commission treats as deceptive if the original price wasn't genuinely offered in the recent past. No equivalent doctrine has been applied to sportsbook odds displays, partly because odds aren't consumer goods and partly because the reference price in sports betting is genuinely ambiguous — there's no single "real" line, just a market consensus that shifts by the minute.
Some operators have begun pre-empting scrutiny on their own. Two of the three operators in the study have since revised their boost displays to include a timestamp and a note indicating the reference price's source. Neither change reduced stake sizes in follow-up observation, though the sample there is too small to be conclusive.
What the state-level patchwork produces
The practical result is that a bettor in Tennessee and a bettor in Virginia can see materially different boost labeling on the same market at the same sportsbook, depending on how aggressively the state has interpreted its advertising rules. That inconsistency is itself a finding: it suggests the industry doesn't have a shared internal standard for what a boost label means, only a shared visual vocabulary for it.
Where the money actually goes
The 24.1% stake increase is not evenly distributed, and the study's demographic breakdown is worth more attention than the headline number. The effect was largest among bettors aged 21–34 (a 31.4% increase in mean stake) and among bettors who self-reported placing more than 10 wagers per week (a 28.7% increase). It was smallest — and in one sub-analysis, statistically indistinguishable from zero — among bettors over 55 and among those who described themselves as "occasional" bettors.
That pattern cuts against the industry's usual defense of promotional labeling, which is that it attracts casual customers and helps them find value. The data here suggests the opposite: the people most responsive to the boost badge are the ones already betting most frequently, and the ones most likely to be exposed to its cumulative effect over time.
A 24% increase in stake size is not, on its own, a harm. If the underlying bets carry the same expected value — and in this study they did — then a bettor staking $34.60 instead of $27.88 is taking on more variance for the same edge, which is a real but bounded cost. The concern is compounding. If a bettor's average stake drifts upward 24% and their win rate holds flat, their bankroll's rate of depletion accelerates in proportion to the increased stake, not the increased edge. Over a season, that's the difference between a recreational budget and a problem.
The study didn't measure harm outcomes, and Alvarez is careful to say so. "We measured behavior, not consequence," she said. "We can tell you stakes went up. We can't tell you what happened to those people six months later. That study hasn't been done."
The responsible-gambling tools nobody touches
Worth noting: none of the three operators in the study altered their deposit-limit or self-exclusion interfaces during the test period, and the treatment group's use of those tools was statistically identical to the control group's. A boost label that raises stakes by nearly a quarter did not, in this sample, trigger any corresponding uptick in players reaching for the brakes. That's not surprising — limit-setting is a deliberate act, and a badge is not — but it does mean the industry's standard responsible-gambling suite is not calibrated to catch this particular nudge.
If you're a bettor trying to gauge your own exposure, the practical version of this finding is unglamorous: track your average stake, not your win rate. Win rate is noisy over any short window and will tell you almost nothing. Average stake is stable, visible in every app's bet history, and is the variable this research says is actually being moved.
The number that should worry operators most
Buried in the study's appendix is a figure that hasn't gotten much attention: 61% of treatment-group participants, when surveyed afterward, said they believed the boosted odds represented a better expected value than the standard odds. They didn't believe the price was the same. They believed it was better.
That's the finding with teeth, because it's the one that turns a behavioral nudge into something closer to a misperception. The badge didn't just increase stakes; it changed what people thought they were buying. And unlike the stake-size effect, which is measurable and bounded, the belief effect is neither. A bettor who thinks they're getting an edge they aren't getting will keep chasing it, and no amount of accurate fine print underneath the badge appears to dislodge the impression.
Operators have a straightforward option here, and it isn't expensive: label the reference price. If the "old" number was a real market price at a real time, say so, with the timestamp. If it wasn't, don't cross it out. That single change would preserve the promotional energy operators clearly want while removing the specific visual element this research identifies as the active ingredient. Whether any operator does it without being told is the open question — and given that the FTC's anchor-pricing doctrine has never been applied to sportsbook odds, the answer may depend on which state attorney general reads this study first.