When an NBA Player Is Listed “Questionable,” Do They End Up Playing?
We count what share of players listed as “Questionable” actually end up playing. Whether the market gets this uncertainty right is the question for the next step.
Study details
On this page
Key findings
2024-25 and 2025-26 regular seasons: the player played in 1,423 of 2,559 cases (range 53%–58%). Key player = averaging 20+ minutes over the last 10 games. Other websites have published similar overall figures, so this part is not a blind test.
- Almost no “Doubtful” players played (1.3%); almost all “Probable” players did (97.3%).
- Players first listed as “Questionable” less than 12 hours before tip-off played only 47% of the time; those listed earlier played 60% of the time.
- Among players still listed as questionable two hours out, 98.6% of those finally cleared played; none of those finally ruled out played in this sample.
- Odds: when the home team has one more “Questionable” key player than the away team, we can’t see which way the odds will move before tip-off (on average only +0.01 percentage points of implied win chance, range −0.23 to +0.25). This doesn’t mean the market got it right — only that this method can’t see a pattern.
In plain words
What do we want to know?
The NBA’s official injury report lists players with statuses such as “Out,” “Doubtful,” “Questionable” and “Probable.” First, we want to know: what share of players listed as “Questionable” actually end up playing? Does it differ by how important the player is, or how long before the game it is? The next step is to check whether the market gets this uncertainty right.
How do we study it?
We will use the official injury reports already parsed in R1 with their release times (the reporting frequency changed; after the mid-2025-26 rule change, roughly every 15 minutes) and player participation records to compute playing rates. Polymarket prices are for the team winning, not for whether a player plays; judging the market means inferring it from changes in the team’s win price, and the method and assumptions will be spelled out in the plan, which is being drafted.
From questionable to actual appearance
- 01Record pre-game status
At a pre-specified time, record whether the player is listed as questionable.
- 02Check the game record
Count players who appeared and those who did not; do not select only appearances.
- 03Calculate appearance rate
Appearances divided by all eligible player-game observations; separate games are counted separately.
- 04Compare conditions
For example, compare time to tip-off and player importance.
This explains the method; see Key findings above for the actual rates. A team’s chance of winning is not a player’s chance of playing.
What have we found?
About 56% of key players listed as questionable two hours before tip-off played; doubtful players almost never did and probable players almost always did. 47.3% of players first listed less than 12 hours out played, versus 59.8% of those listed earlier. On odds, the status did not predict later moves.
How does this help with predictions?
Treat “questionable” as “a bit more than half will play” rather than certain either way. In this sample, players first listed less than 12 hours before tip-off played less often overall—but the second game of a back-to-back is often listed late because of the reporting rules, so do not lower the chance across the board. Players finally cleared almost always play.
What can’t we say yet?
Polymarket only has odds on “will the team win”; there is no market on “will the player play.” So this version does not judge whether the market gets playing chances right. Seeing no change in the odds only means this method couldn’t see one (a change needs to be about 0.34 percentage points or more to show up). Other websites have published some playing rates, so part of our numbers is not a blind test.
Terms used on this page
- Questionable
- A status on the NBA injury report meaning it is still uncertain whether the player can play.
- Team win odds
- The odds on Polymarket that “a certain team will win,” which roughly show the chance people think that team has of winning. They are not odds on whether a player will play.
Detailed results
Share who actually played, by injury status 2 hours before tip-off
Key players (averaging 20+ minutes over their last 10 games), 2024-25 and 2025-26 regular seasons.
Calculated following the plan written in advance｜Status taken at the moment 2 hours before tip-off, and already posted for at least 15 minutes｜“Listed early” = first listed 12 hours or more before tip-off; “listed late” = less than 12 hours｜Played = has an appearance in the official game stats (including under 1 minute).
HypothesesFor deeper reading
- H1Being listed as “Questionable” 2 hours before tip-off predicts how the odds change until tip-off → not seen (+0.01 percentage points of implied win chance, range −0.23 to +0.25)Insufficient evidence
- H2The “Doubtful” status predicts changes in the odds → not seenInsufficient evidence
- H3The “Probable” status predicts changes in the odds → a little when looked at alone, but it doesn’t hold after correcting for testing several things at once; the two seasons also point in different directionsInsufficient evidence
- H4The playing rate for “Questionable” differs by how important the player is → slightly higher for stars (57% vs. 54%), but it doesn’t hold after the correctionInsufficient evidence
- H5Second night of a back-to-back differs → supported in the model, but both raw rates are about 56%. A split added after seeing the results shows 536 of 540 back-to-back cases were listed late; this helps explain the model gap but does not show back-to-backs themselves change playing ratesSupported in this sample
- H8Players first listed as “Questionable” less than 12 hours before the game have a different playing rate → holds (47% vs. 60%)Supported in this sample
Background and why it matters
“Questionable” is the most uncertain and also the most common status on the injury report. Turning it into a playing rate helps the model estimate each game’s lineup more accurately.
Latest progress
Latest：Main results are in; report wording corrected after external code review
Next step：Publish after confirming data licensing; check again on the new 2026-27 season using rules that are already locked
Study timeline
- Novelty checked; plan finalized and timestamped after two rounds of external code review2026-10-21
- Data organized; all six checkpoints passed2026-10-21
- Main analysis done; corrected after external code review2026-10-21
- Publish after confirming data licensingIn progress
- Check again on new 2026-27 games
Methods
What we want to know
- What share of players listed as “Questionable” actually end up playing? Does it differ by how important the player is, whether the team played the day before, or how long before the game it is?
- Can the injury status 2 hours before tip-off predict how the odds change from then until tip-off?
Method summary
- Playing rate: key players (averaging 20+ minutes over their last 10 games) in the 2024-25 and 2025-26 regular seasons. We take their status on the official injury report 2 hours before tip-off and check the official game stats for whether they played.
- Odds: 1,091 games in the 2025-26 season, comparing Polymarket odds 2 hours and 5 minutes before tip-off. For every game, we checked that the final odds reading came before the game actually started.
- There is only one main test (H1). The other five are corrected together for testing many things at once, to avoid “try enough times and something will hit by luck.”
- We hand-checked 40 player-games against the game stats on the NBA’s official website: 0 errors. All six data checkpoints passed.
Data and limitations
Data we use (all public and free)
- Official NBA injury reports (already organized in R1)
- NBA player game-by-game playing records
- Polymarket odds for single NBA games
Limitations
- Polymarket only has odds on “will the team win,” so this version neither estimates nor judges what the market thinks a player’s chance of playing is.
- We have one odds reading every 5 minutes, with no buy and sell prices; only changes of about 0.34 percentage points or more can be seen.
- The trading volume cutoff for the price sample uses total volume collected after the games, so it can’t be used directly as a rule for picking games before they start.
- Other websites have published some playing rates that overlap with our sample, so the playing rates are not a blind test.
Update log
Version history
- v1.0-results2026-10-21
Main results are in; after an external code review, we fixed the report’s wording (not describing “no drift seen” as “the market got it right”) and added a code check
- v1.02026-10-21
Study plan finalized and timestamped (this first version does not judge whether the market gets playing chances right)
Study record
d687a2aa3c048468c1436f58d688e1a9b5a1f776689653f5dcf8dac215b8007a049743c91b6bcbe505f26cc381ea4c6ef415d4ee2bd06f53ab621e35cb9723dbThis page is a research log for reference only and is not betting advice or a guarantee of profit.