How many mass shootings will the Mass Shooting Tracker record in the United States between May 25 and June 8, 2026?

• My most likely prediction for the number of mass shootings recorded by the Mass Shooting Tracker between May 25 and June 8, 2026, is 13.50, with a 50% chance of falling between 11.50 and 13.50.
• Current 2026 data shows 186 incidents recorded through May 18, indicating a year-to-date average of approximately 1.35 incidents per day.
• Historical data from 2024 and 2025 shows a distinct seasonal surge in incidents during late May and early June, often exceeding 1.7 incidents per day.
• While incident counts are expected to rise seasonally, broad 2026 crime statistics indicate a 17.7% decline in nationwide homicides, which may temper the total count.
• The inclusive definition used by the Mass Shooting Tracker (counting four people shot, including perpetrators) historically results in higher counts than FBI or Gun Violence Archive datasets.
• Weather forecasts for the late May period predict heavy rainfall and cooler temperatures in high-incident regions, which could potentially lower outdoor violence rates.

Key figures

Historical context

The Mass Shooting Tracker (MST) has documented a consistent seasonal pattern where mass shooting incidents increase in frequency during the late spring and summer months. Historical data highlights this trend: in 2024, May saw 53 incidents and June rose to 79; in 2025, May recorded 45 and June saw 59. Since 2011, MST’s more inclusive definition (requiring four or more shot rather than four or more killed) has generally yielded an average of approximately one incident per day nationwide. However, the post-2020 period saw a dramatic spike, with the US homicide rate jumping to 6.35 per 100,000 in 2020 and 6.78 in 2021 before beginning a decline to 5.76 in 2023. This historical volatility shows that while the long-term trend (30+ years) is downward, the metric is highly susceptible to sudden yearly shocks. The period of May 25 to June 8 specifically encompasses the transition from the Memorial Day holiday into the start of summer, a window that historically captures high-profile public and domestic clusters.

Tailwinds

• The Mass Shooting Tracker’s definition includes perpetrators in the casualty count, which captures more incidents than databases requiring four fatalities excluding the shooter.
• Current May 2026 data indicates a significant recent surge, with 52 incidents recorded in the first 18 days of the month (2.89 per day).
• Historical seasonal trends consistently show a sharp increase in gun violence as temperatures rise between May and July.
• Chicago, a major contributor to MST data, has seen homicides rise in 2026 despite the national downward trend, reporting 152 homicides through mid-May.
• Reduced federal funding for community violence intervention organizations in certain cities has been cited as a factor in recent shooting upticks.

Headwinds

• Major Cities Chiefs Association data indicates a 17.7% nationwide decrease in homicides and a 20.4% decrease in robberies during Q1 2026.
• The Trace reports that gun deaths in Q1 2026 reached their lowest level in 12 years, with nearly 500 fewer fatalities than the same period in 2025.
• Law enforcement agencies in several major cities, including San Diego, Washington D.C., and Philadelphia, report homicide declines of over 50%.
• Significant precipitation and cooler temperatures forecast for the East Coast and Texas during the late May period could suppress outdoor gatherings and related violence.

Detailed reasoning

My prediction for the number of mass shootings recorded by the Mass Shooting Tracker (MST) between May 25 and June 8, 2026, is based on a synthesis of year-to-date (YTD) 2026 data, historical seasonal trends, and current law enforcement reporting on violent crime.

First, I examined the YTD performance of the MST in 2026. As of May 18, 186 incidents had been recorded. The monthly progression showed 26 in January, 31 in February, 41 in March, and 36 in April. This cumulative total suggests an average of approximately 1.35 incidents per day across the first 138 days of the year. Applying this daily rate to the 15-day target window results in a baseline expectation of 20.25 incidents. However, the data for May 1–18, 2026, indicates a localized surge with 52 incidents in just 18 days (2.89 per day), suggesting that the late-spring seasonal increase is already underway.

Second, I integrated historical seasonal patterns. Mass shootings in the U.S. traditionally peak during the summer months. Historical MST data for May and June shows high totals: 53 and 79 respectively in 2024, and 45 and 59 in 2025. A 15-day window in late May/early June typically captures the start of this peak. In fact, a similar 15-day window in 2025 recorded 27 incidents using Gun Violence Archive (GVA) criteria. Since the MST definition is more inclusive (counting perpetrators as victims if shot), the MST figure for such a window is statistically likely to be equal to or higher than GVA figures.

Third, I adjusted for broader 2026 crime trends. Major Cities Chiefs Association data for the first quarter of 2026 shows a significant 17.7% drop in homicides nationwide. Cities like Washington D.C., Philadelphia, and New York have seen decreases in lethal violence exceeding 30%. This “cooling” of the macro-environment suggests that while incident counts will rise seasonally, they may not reach the extreme peaks seen in 2021 or 2024.

I weighted the current 2026 YTD average and the recent May surge most heavily, as they represent the most immediate environment. However, I also factored in potential reporting lags, as the resolution criteria specify a measurement date only one week after the window closes (June 15). This could result in a slightly lower recorded count than the “final” year-end tally. Balancing the baseline of ~20 incidents against the current 2026 downward trend in overall violent crime, I arrived at a most likely value of 13.5 incidents. This value reflects a count that is high relative to the winter months but moderated compared to the raw seasonal projections from prior years. The 50% HDI of 11.5 to 13.5 reflects the typical volatility seen in two-week observation windows for this specific metric.

Key uncertainties

• The resolution relies on a June 15 observation date, which may miss late-reported or backfilled data for the final days of the window.
• Crowd-sourced reporting frequency on the Mass Shooting Tracker can vary based on news cycle intensity and volunteer activity levels.
• Mass shooting events often occur in clusters; a single high-profile weekend (e.g., Memorial Day) can significantly skew a 15-day window.
• Changes in police reporting transparency in major metropolitan areas can affect the “raw” count available to trackers.
• Variations in localized weather patterns (e.g., severe storms vs. heat waves) have a direct, non-linear impact on urban gun violence.

Conclusion

• The predicted count of 13.5 incidents is significantly higher than the average monthly run rates seen in early 2026, driven primarily by the transition into the historically violent summer season.
• While broader violent crime indicators show a 17-18% decline in 2026, the Mass Shooting Tracker’s inclusive definition (which includes perpetrators) often captures a higher volume of incidents than traditional law enforcement databases.
• The 15-day window specifically encompasses the post-Memorial Day period, which traditionally sees elevated incident counts compared to the winter months.

The question asks whether the Mass Shooting Tracker (MST) count for May 25–June 8, 2026 (resolved on the MST 2026 page on June 15) will fall into the market’s open top bin of 15+ incidents. Forecasters largely agree that the direct MST checkpoints and same-window analogues point strongly to 15+: secondary reports show MST rising by roughly 25 incidents in each prior ~14–15 day period (Apr. 20–May 18), and hand-counted broad “4+ shot” analogues for May 25–June 8 in 2022–2025 range from about 27–39 incidents. Seasonality (Memorial Day start and early-summer uptick) and near-real-time local reports further support an elevated pace, while adjacent datasets (GVA/Everytown/The Trace) show mass-shooting activity up in early 2026 despite mixed broader crime trends. Key shared caveats are definitional mismatches between MST and proxy datasets, MST’s crowd-sourced revision and reporting lag (the market resolves one week after the window), and the small but nontrivial chance of an abrupt lull or missing entries that could push the count to ~10–14. Given these factors, teams place very high probability on the 15+ bin (one team ~94%) while keeping modest probability mass in the 10–14 range to reflect revision/lag risk.

Forecast and Reasoning

Forecast: Probability distribution:

• 5.00% chance of value below 9.5
• 10.00% chance of value below 12.8
• 20.00% chance of value below 14.3
• 30.00% chance of value below 15.2
• 40.00% chance of value below 15.9
• 50.00% chance of value below 16.5
• 60.00% chance of value below 16.9
• 70.00% chance of value below 17.2
• 80.00% chance of value below 17.45
• 90.00% chance of value below 17.6
• 95.00% chance of value below 17.74

Forecast Reasoning

We are forecasting the number of incidents MassShootingTracker.site will list (as of June 15, 2026) with dates May 25–June 8, 2026 inclusive (15 days). The dominant uncertainty is the underlying incident rate the tracker is currently recording, plus short-window volatility and any data-entry lag.

Across analyst research, three of four forecasters report that the tracker’s 2026 YTD count as of mid/late May is around 187–188, implying roughly 1.3+ incidents/day. At that pace, a 15-day window would have an expected count near 20, making >14 incidents more likely than not. A fourth forecaster instead used a lower annualized rate (~1/day) and produced a median near 11; I treat that as a plausible-but-less-supported scenario (it could reflect a different definition/series, partial updates, or simple rate misestimation).

Historical same-calendar windows cited by one analyst (2013–2015 giving roughly 12–19 incidents for this 15-day span) support that (a) outcomes in the low teens are possible, but (b) high teens are also common even in earlier years. The one-week-later observation date (June 15) should capture most events, but some residual undercount risk remains.

Net: I center the distribution on “high teens/low 20s true count”, but because the platform’s open upper bound is 14.0, I focus on calibrating the exceedance probability. I estimate roughly 80% (order-of-magnitude 75–90%) chance the realized count exceeds 14, with a meaningful (but minority) chance it lands in the 10–14 range.

An amateur forecast is likely to (1) anchor on high-profile public shootings (far lower base rate than MST’s 4+ shot definition), or (2) overweight the creator note that “likely not higher than 14” without reconciling it to the tracker’s apparent 2026 YTD pace. My forecast instead triangulates on (i) multiple analysts’ direct checks of MST’s 2026 pace and (ii) historical same-window counts, and then explicitly represents substantial probability mass above the open upper bound rather than forcing all percentiles to remain ≤14. Confidence in the improvement is medium: the key remaining risk is that the reported YTD pace is wrong or not comparable to this question’s definition, which would shift the whole distribution downward.

Forecast rationale (numeric):

— Iteration 1 — Across the forecasts, the main reasoning is:

• Baseline rate is the anchor: Recent 2026 data suggests roughly 1.07–1.12 mass shootings per day, which over a 15-day window implies about 16–17 incidents.
• Seasonal and calendar effects matter: The period includes Memorial Day weekend, which some expect to lift counts, and June is viewed as somewhat higher-risk than spring.
• Tracker/reporting lag is a major adjustment: Because the Mass Shooting Tracker is crowdsourced and updated with delay, some forecasts reduce the raw baseline to account for incidents that may not yet be logged by the observation date.
• Short-window volatility is high: All rationales emphasize overdispersion and clustering, meaning a 15-day total can deviate substantially from the daily average. This leads to wide uncertainty bands.
• Tail assumptions differ: Lower bounds range from 0 up to a cautious floor, while upper tails extend well above 25 to capture holiday clustering or unusually active stretches.

Areas of consensus

• The expected count is driven primarily by a recent daily rate near 1.1/day.
• There is meaningful uncertainty because the window is short and the source is lagged.
• The most likely outcome is in the mid-teens, not extremely low.

Main disagreement

• One view leans toward ~13 incidents to reflect reporting lag and a soft upper constraint.
• Others keep the estimate closer to the raw rate, around 16–17 incidents, with holiday effects potentially pushing slightly higher.

Overall synthesis

The forecasts converge on a mid-teens expectation, with the final number shaped by the tension between a stable recent base rate and downward adjustment for tracker lag, partially offset by holiday/early-summer uplift.

— Iteration 2 — Across the forecasts, the main reasoning is that Mass Shooting Tracker’s broad 4+ shot definition and the 15-day window spanning Memorial Day and early-summer weekends should produce a count in the low teens, with holiday/weekend effects nudging the number upward.

Key factors driving the estimates

• Definition matters: The tracker’s inclusive “4+ shot” standard tends to generate higher counts than narrower mass-shooting definitions.
• Seasonality and calendar effects: Memorial Day weekend and early summer are treated as periods with somewhat elevated violence risk, supporting a modest bump in expected incidents.
• Tracker reliability/capacity: Several rationales note that the tracker may be incompletely maintained or subject to reporting delays, which pulls the estimate down relative to what a fully active system might capture.
• Broader violence trend: Some reasoning points to recent declines in U.S. gun violence, reinforcing a central estimate below pandemic-era peaks.
• Clustering and volatility: Mass-shooting counts over short windows are seen as overdispersed and bursty, so the distribution is right-skewed with a meaningful chance of unusually high or low outcomes.

Areas of consensus

• The expected count is roughly in the low teens, not single digits and not extremely high.
• Most probability mass is seen as below about 15 incidents.
• There is strong agreement that the outcome has substantial uncertainty, with a long upper tail from clustered events or more complete reporting.

Main disagreement

• The main divergence is about how active/comprehensive the tracker will be during the period:
  • If coverage is solid, the count could be notably higher.
  • If the site is sparse or delayed, the total could land closer to the lower end of the low-teens range.

Overall, the forecasts combine calendar-based uplift, broad definition effects, and tracker incompleteness to arrive at a modestly elevated but still constrained expectation, with a right-skewed distribution reflecting upside risk from bursts in incidents or reporting.

— Iteration 3 — The forecasts largely converge on a low-teens expectation for the 15-day window, but with a wide uncertainty band.

Main reasoning patterns

• Base-rate extrapolation: All models start from the recent 2026 pace of roughly 1.07 incidents per day, which mechanically implies about 16 events over 15 days.
• Memorial Day seasonality: The window includes Memorial Day weekend, which is treated as a modest upward driver because holiday periods can see elevated incident counts.
• Reporting lag / tracker incompleteness: A major downward adjustment comes from the fact that Mass Shooting Tracker is crowd-sourced and can lag by several days, meaning incidents near the end of the window may not be recorded by the cutoff.
• Soft upper-bound guidance: The prompt’s implication that the answer is likely below 14.5 strongly anchors the forecasts downward from a pure base-rate extrapolation.
• Bursty distribution and tail risk: Even with a low central estimate, the models keep a substantial upper tail because shootings cluster unpredictably, and a single high-activity period can push totals much higher than average.

Areas of consensus

• The central estimate should be below the simple 16-event extrapolation.
• The most likely outcome is around 11–13 incidents, not in the high teens.
• The distribution is asymmetric, with more concern about occasional spikes than about very low counts.

Main disagreement

• One view emphasizes recent base rates and holiday uplift, keeping the center closer to the mid-to-high teens.
• The others weigh reporting lag and the prompt’s soft cap more heavily, pulling the estimate down toward 11–13.

Overall synthesis

The collective reasoning suggests that the best forecast is a low-teens count, with the Memorial Day effect raising expectations somewhat, but tracker lag and the explicit “below 14.5” cue preventing a pure extrapolation from dominating.

Here is a synthesis of the qualitative reasoning shared across the 10 rationales:

Base Rates and Current Trends The rationales agree that the Mass Shooting Tracker (MST) utilizes a highly inclusive definition of mass shootings (four or more individuals shot, including the perpetrator), which structurally yields higher incident counts than stricter databases. Year-to-date data for 2026 shows an upward trend compared to the historic lows of 2025, though it remains notably lower than the pandemic-era peaks of 2021–2023. Because the current 2026 average largely reflects the colder winter and early spring months, forecasters treat it as a baseline floor rather than a ceiling for the target period.

Seasonality and Calendar Effects Gun violence is historically seasonal, with a predictable “summer surge” driven by warmer weather, longer daylight hours, and an increase in outdoor social gatherings. The rationales note that forecasted unseasonable heat and potential El Niño effects during the target window will likely amplify interpersonal violence. Furthermore, mass shootings are heavily concentrated on weekends and holidays. The 15-day window includes two full standard weekends and Memorial Day Monday. However, forecasters carefully highlight that the window excludes the Saturday and Sunday immediately preceding Memorial Day—the days that traditionally see the heaviest volume of holiday violence—which tempers the expected holiday spike.

Contagion and Social Factors Multiple rationales incorporate the potential for a short-term “contagion” or copycat effect stemming from a high-profile, ideologically driven attack on May 18. Academic literature suggests a roughly two-week contagion window following such events, which overlaps with the first week of the forecasting period. Additionally, generalized civil unrest and ongoing protests are cited as systemic risk factors that could marginally elevate the threat environment.

Reporting Methodology and Resolution Lag The forecasting question resolves based on data visible on the MST site exactly one week after the target window closes. Because the MST is a crowdsourced, volunteer-run tracker heavily reliant on media reporting, it inherently experiences data entry delays. While forecasters agree that a seven-day buffer is largely sufficient to capture the vast majority of incidents, most apply a slight downward adjustment to their estimates to account for obscure, rural, or late-window incidents (e.g., from June 7–8) that may miss the resolution cutoff due to verification lags.

Variance and Uncertainty Finally, all rationales recognize that mass shootings follow an overdispersed distribution, meaning they are highly volatile and prone to unpredictable clustering. Because short-term lulls and sudden weekend spikes are common, forecasters universally support maintaining wide confidence intervals to account for both unusually quiet stretches and severe, heat-driven clusters.

SUMMARY

Question: How many mass shootings will the Mass Shooting Tracker record in the United States between May 25 and June 8, 2026? Final Prediction: Probability distribution:

• 10.00% chance of value below 8.83
• 20.00% chance of value below 14.163333
• 40.00% chance of value below 20.163333
• 60.00% chance of value below 24.996667
• 80.00% chance of value below 30.363333
• 90.00% chance of value below 35.33

Total Cost: extra_metadata_in_explanation is disabled Time Spent: extra_metadata_in_explanation is disabled LLMs: extra_metadata_in_explanation is disabled Bot Name: extra_metadata_in_explanation is disabled

Report 1 Summary

Forecasts

Forecaster 1: Probability distribution:

• 10.00% chance of value below 13.6
• 20.00% chance of value below 16.6
• 40.00% chance of value below 20.6
• 60.00% chance of value below 24.1
• 80.00% chance of value below 28.2
• 90.00% chance of value below 32.1

Forecaster 2: Probability distribution:

• 10.00% chance of value below 7.4
• 20.00% chance of value below 14.4
• 40.00% chance of value below 21.4
• 60.00% chance of value below 26.4
• 80.00% chance of value below 32.4
• 90.00% chance of value below 38.4

Forecaster 3: Probability distribution:

• 10.00% chance of value below 5.49
• 20.00% chance of value below 11.49
• 40.00% chance of value below 18.49
• 60.00% chance of value below 24.49
• 80.00% chance of value below 30.49
• 90.00% chance of value below 35.49

Research Summary

The research summarizes recent Mass Shooting Tracker data and historical/seasonal patterns to produce a short-range forecast for May 25–June 8, 2026. As of May 18, 2026 the Mass Shooting Tracker had recorded 186 mass shootings year-to-date; recent notable incidents cited include the San Diego Islamic Center attack on May 18 and a White House shooting on May 23. The 2026 year-to-date rate is calculated at 1.35 mass shootings per day (186 events over ~138 days). Historical comparisons use Mass Shooting Tracker 2024 monthly and annual rates (May 2024 = 1.71/day, June 2024 = 2.63/day, 2024 annual average = 1.60/day), and note a documented seasonal pattern with summer months—especially June and July—typically showing elevated mass-shooting activity.

For the 15-day forecast window (7 days late May including Memorial Day weekend + 8 days early June), the research presents three rate-based scenarios: a conservative estimate using the 2026 YTD rate (1.35/day) yields ~20 shootings; a moderate seasonal adjustment (late May 1.5/day, early June 2.0/day) yields ~26–27 shootings; and a higher estimate applying 2024 seasonal rates yields ~33 shootings. The analysis notes adjustments and caveats—Gun Violence Archive reporting of lower 2026 violence levels relative to 2024, Memorial Day weekend effects, the May→June seasonal increase, possible reporting lags and definitional issues with the Mass Shooting Tracker—and concludes with a recommended central forecast range of 23–26 shootings (most likely 24–25), plus stated uncertainties about seasonal magnitude, holiday effects, definition consistency, and late reporting.

Sources used (as cited in the research):

• Mass Shooting Tracker — https://www.massshootingtracker.org
• Gun Violence Archive — https://www.gunviolencearchive.org
• Kalshi — https://www.kalshi.com
• Polymarket — https://polymarket.com

(The research also referenced news reports of the May 18, 2026 San Diego Islamic Center attack and the May 23, 2026 White House shooting; specific article links were not provided in the research summary.)

RESEARCH

Report 1 Research

Based on my research into historical data, current trends, and seasonal patterns, here is a comprehensive analysis to inform your forecast:

Current Context (as of May 24, 2026)

As of May 18, 2026, the Mass Shooting Tracker had recorded 186 mass shootings in the United States for the year [1][10]. Recent incidents include the San Diego Islamic Center attack on May 18, 2026, which killed three people [1][2][9], and a White House shooting on May 23, 2026 [3][11][15].

Base Rates and Historical Data

2026 Year-to-Date Rate:

• 186 shootings over approximately 138 days (Jan 1 - May 18)
• Daily rate: 1.35 mass shootings per day [1][10]

2024 Historical Comparison (using Mass Shooting Tracker definition):

• May 2024: 53 mass shootings over 31 days = 1.71 per day [28]
• June 2024: 79 mass shootings over 30 days = 2.63 per day [28]
• 2024 Annual: 587 total mass shootings = 1.60 per day average [28]

Key Seasonal Pattern: Research shows that “deadliest months for mass shootings in the U.S. tend to be summer months, especially June and July” [19]. June consistently shows elevated rates compared to other months.

Forecast Period Analysis (May 25 - June 8, 2026)

The 15-day forecast period includes:

• 7 days in late May (May 25-31, including Memorial Day weekend on May 26)
• 8 days in early June (June 1-8)

Rate Projections:

1. Conservative estimate (using 2026 YTD rate of 1.35/day):

• 15 days × 1.35 = 20 shootings

2. Moderate estimate (accounting for seasonal increase):

• Late May at 1.5/day × 7 days = 10.5
• Early June at 2.0/day × 8 days = 16
• Total: 26-27 shootings

3. Higher estimate (using 2024 seasonal rates):

• Late May at 1.71/day × 7 days = 12
• Early June at 2.63/day × 8 days = 21
• Total: 33 shootings

Important Adjustments:

• Gun Violence Archive reports that mass shootings in 2026 have “declined to pre-COVID levels” with significant decreases in gun violence deaths and injuries [16]
• The 2026 rate (1.35/day) is notably lower than 2024’s average (1.60/day)
• Memorial Day weekend historically sees elevated gun violence
• The transition from May to June represents a shift into peak summer violence season

Prediction Markets

No specific prediction markets found for this question. My search revealed extensive information about Kalshi and Polymarket [22-25], including:

• Congressional investigation into insider trading launched May 22, 2026 [23]
• Kalshi’s annualized trading volume: $178 billion [25]
• Polymarket’s monthly volume: ~$10.3 billion in April 2026 [25]

However, no markets were identified specifically forecasting mass shooting counts for this time period. This may be due to ethical concerns or prohibitions on betting on violent events.

Recommended Forecast Range

Given the seasonal transition, Memorial Day weekend effect, and 2026’s lower overall rate:

Central estimate: 23-26 mass shootings

• Low range: 20-22 (if 2026 trends continue)
• High range: 28-33 (if June seasonal spike is pronounced)

The most likely outcome appears to be in the 24-25 range, representing a balance between 2026’s lower baseline rates and the historical June seasonal increase.

Key Uncertainties

1. Seasonal effect magnitude: Unclear if June 2026 will match June 2024’s elevated rates
2. Memorial Day weekend: Holiday weekends often see spikes, but magnitude varies
3. Definition consistency: The Mass Shooting Tracker uses a broad definition (4+ shot, regardless of fatalities)
4. Data finalization: The question resolves based on June 15 observation, allowing for late-reported incidents

FORECASTS

R1: Forecaster 1 Reasoning

Conditional on the question resolving normally and not being annulled:

(a) Time left until outcome is known:
The event window is May 25–June 8, 2026 inclusive, and the value is observed on June 15, 2026. From today, May 24, 2026, that is 1 day until the window opens, 15 days in the window, and 22 days until the resolution observation date.

(b) Outside view:
The most relevant reference class is U.S. mass-shooting counts under a broad “4+ shot” definition over a 15-day late-spring/early-summer window. The research assistant’s MST-based base rates imply:

• 2026 YTD: 186 incidents through May 18, or about 1.35/day, which would imply 20.3 incidents over 15 days.
• 2024 annual MST: 587 incidents, or 1.60/day, implying 24.1 incidents over 15 days.
• 2024 May/June seasonal rates: May 53 and June 79; applying those month rates to 7 late-May days and 8 early-June days gives roughly 33 incidents, though that may overweight a hot 2024 summer.

The Mass Shooting Tracker definition is broad: it counts incidents with 4 or more people shot, and unlike Gun Violence Archive, it can include the shooter’s death/injury in the count. (massshootingtracker.site)

(c) Inside view:
I update downward from the pure 2024 May/June seasonal estimate because broader 2026 gun-violence indicators look lower than the 2021–2023 peak period, and because the window includes only Memorial Day itself, May 25, not the full preceding Memorial Day weekend. The Trace reports Q1 2026 shooting deaths were the lowest Q1 figure in a dozen years, while GVA recorded 94 Q1 2026 mass shootings—above Q1 2025 but below 2021–2023 levels. (thetrace.org) Pew also reports a GVA mass-shooting decline from 690 in 2021 to 502 in 2024. (pewresearch.org) I update upward relative to a very low forecast because this is a broad crowd-sourced tracker, the period includes two weekends and the start of June, and the one-week reporting lag to June 15 should catch some late-reported incidents.

(d) Outcome if nothing changed:
If no new qualifying incidents were added for the target dates, the outcome would be 0 incidents. That is not my substantive forecast; it is just the “no change/no new entries” mechanical value.

(e) Outcome if the current trend continued:
Using the research report’s 2026 YTD rate of 1.35/day, the direct trend continuation gives about 20 incidents. With modest seasonal adjustment for early June, I’d put the trend-continuation value around 22–24 incidents.

(f) Expectations of experts and markets:
The research report found no specific prediction markets for this question. Data-oriented expert sources point in mixed directions: gun violence is down from peak-era levels, but broad-definition mass shootings remain frequent, and Q1 2026 GVA mass shootings were not unusually low versus 2025. (thetrace.org)

(g) Unexpected low-outcome scenario:
A low outcome, say 10–14 incidents, could happen if early June is unusually quiet, Memorial Day violence is concentrated on May 23–24 rather than May 25, and the tracker misses or delays several local incidents past June 15.

(h) Unexpected high-outcome scenario:
A high outcome, say 30+ incidents, could happen if the June seasonal spike resembles 2024, with multiple party/nightlife/large-gathering shootings on the May 30–31 and June 6–7 weekends, plus several late additions by June 15.

Rationale:
I anchor on the 2026 YTD MST base rate, which points to about 20 incidents. The annual 2024 base rate points somewhat higher, around 24, and the May/June 2024 seasonal pattern points much higher, around 33. I discount the full seasonal estimate because current broader gun-violence indicators are lower than the 2021–2023 peak and because the window misses most of Memorial Day weekend. Still, the broad MST definition and the early-June timing make the question creator’s “likely not higher than 14” look too low to me. My central forecast is therefore about 22 incidents, with substantial dispersion from reporting uncertainty and clustering.

Percentile 0.1: 3.49
Percentile 1: 7.49
Percentile 5: 10.49
Percentile 10: 13.60
Percentile 20: 16.60
Percentile 30: 18.60
Percentile 40: 20.60
Percentile 50: 22.40
Percentile 60: 24.10
Percentile 70: 25.90
Percentile 80: 28.20
Percentile 90: 32.10
Percentile 95: 35.00
Percentile 99: 41.00
Percentile 99.9: 48.00

R1: Forecaster 2 Reasoning

Conditioning on not annulled, but not conditioning on the Mass Shooting Tracker page behaving normally. I accept the critic’s core point: this is partly a webpage-resolution forecast, not just a violence-rate forecast.

The strongest valid criticism is source-state risk. When I fetch the resolution URL with ?year=2026, it still renders as “Mass Shootings in 2025” and shows visible JSON links only through 2025. That may be a crawler/static-rendering artifact, but it is direct evidence that a June 15 observation could produce a broken/default-year/partial-update outcome. The FAQ also says the project is unfunded and crowd-sourced, with errors, removals, and missed incidents possible. I am therefore moving more probability into exactly 0 / near-zero outcomes than before. (massshootingtracker.site)

I still defend the median being in the low 20s rather than near the creator’s “likely not higher than 14.” The Mass Shooting Tracker definition is broad: four or more people shot, and it includes the shooter’s death; that can count cases that GVA-style definitions exclude. Media reports citing MST gave 144 mass shootings around April 23 and 186 by May 18, implying a recent operational pace around the mid-1s per day, enough to put a normal-functioning 15-day branch in the low-to-mid 20s before much additional seasonality. (massshootingtracker.site)

I also keep some upward seasonal pressure: historical broad/list-style monthly stats show May/June as elevated — e.g. 2024 at 53/79 and 2025 at 45/59 for May/June. But the critic is right that this window starts on Memorial Day Monday, May 25, 2026, excluding the higher-risk Saturday/Sunday of Memorial Day weekend, and includes only June 1–8, not later-June or July 4-adjacent effects. (en.wikipedia.org)

My revised mental mixture is roughly: 4–6% exact-zero/default-page risk; another 5–8% partial-update or creator-was-seeing-source-weirdness risk in the low single digits to low teens; most remaining mass on a normal broad-definition count around 18–33; and a trimmed but real high tail for hot weekends, backfill, threshold cases, or data oddities. I keep the median at 23.4, but make the bottom tail much lumpier and shave the most extreme upper tail.

Updated prediction:
Percentile 0.1: 0.1
Percentile 1: 0.39
Percentile 5: 0.49
Percentile 10: 7.4
Percentile 20: 14.4
Percentile 30: 18.4
Percentile 40: 21.4
Percentile 50: 23.4
Percentile 60: 26.4
Percentile 70: 29.4
Percentile 80: 32.4
Percentile 90: 38.4
Percentile 95: 44.4
Percentile 99: 52.4
Percentile 99.9: 64.4

R1: Forecaster 3 Reasoning

Conditioning on the question not being annulled.

I accept the critic’s main point: this forecast should not be treated as merely “how many broad-definition mass shootings will occur?” The resolution is the MST 2026 data page as observed on June 15, and that creates real plumbing/update risk. My fresh check still shows the nominal year=2026 data page rendering as “Mass Shootings in 2025”, with visible year/JSON links only through 2025; clicking through the site’s data link similarly lands on the 2025 view. That is more than cosmetic and justifies a meaningfully fatter low tail. (massshootingtracker.site)

I also agree that MST’s crowd-sourced nature pushes the one-week snapshot risk downward: MST says errors can occur, entries can be removed, and some incidents are missed; for a June 15 observation of a window ending June 8, delayed entry is more likely to lower the resolved count than raise it. (massshootingtracker.site)

Where I still resist the critic is making the operational failure scenario too dominant. MST’s definition is broad—4+ people shot, including the shooter’s death—which supports a high substantive base rate under normal operation. (massshootingtracker.site) The Independent reported MST at 186 U.S. mass shootings as of May 18, 2026, implying about 20 incidents over 15 days before any seasonality adjustment. (the-independent.com) The prompt itself also asserts that a 2026 MST page/list existed recently enough to name the May 18 San Diego attack as the latest recorded incident, so I do not want to assign a huge probability to literal zero.

Substantively, 2026 does not look like a collapse, but it also does not look like a 2024-style surge. The GVA/Wikipedia-style 2026 list had 134 shootings through April 30, with monthly counts of 26, 31, 41, and 36; The Trace reported 94 GVA mass shootings in Q1 2026, above Q1 2025 but below 2021–2023 levels. (en.wikipedia.org) Historical May/June seasonality still matters—2025 had 45 in May and 59 in June, while 2024 had 53 in May and 79 in June—but the target window starts on Monday, May 25, missing the preceding Saturday/Sunday of Memorial Day weekend, so I now make the holiday uplift modest. (en.wikipedia.org)

My revised model is: normal-operation center around 23–24, mixed with a substantial stale/partial/update-lag component that can yield 0–14, plus a smaller cluster/backfill upper tail. I am moving slightly further toward the critic: median down to about 22, lower 5th/10th/20th percentiles, and modestly trimmed far upper tail.

Updated prediction:
Percentile 0.1: 0.09
Percentile 1: 0.29
Percentile 5: 1.49
Percentile 10: 5.49
Percentile 20: 11.49
Percentile 30: 15.49
Percentile 40: 18.49
Percentile 50: 21.49
Percentile 60: 24.49
Percentile 70: 27.49
Percentile 80: 30.49
Percentile 90: 35.49
Percentile 95: 40.49
Percentile 99: 47.49
Percentile 99.9: 55.49

Agent Forecast (discrete, confidence: medium)

• 15+: 82.9%
• 14: 4.1%
• 13: 3.4%
• 12: 2.8%
• 11: 2.2%

Base Rate: MST 2026 YTD: 188 incidents / 143 days = 1.315/day → 19.7 expected in 15 days. Seasonal uplift for Memorial Day / early summer ~5–8% offsets reporting lag discount of 1–2 incidents; net central estimate λ ≈ 19. MST runs ~25% above GVA due to inclusion of shooter in the 4-person threshold.

Initial Reasoning:

• Trajectory 1 reasoning

  The Mass Shooting Tracker shows 188 incidents in 2026 through May 24 (144 days = 1.31/day), with the data page snippet confirming 1.33/day.
• For the 15-day window May 25–June 8, the base-rate expectation is ~19–20 incidents (15 × 1.31 = 19.6).
• MST records ~25% more incidents than GVA (188 vs 151 through late May) due to its broader definition that includes perpetrators in the 4-person count.
• The window begins on Memorial Day weekend (May 25–26, 2026), historically the highest-violence period of the year, providing a seasonal uplift.
• GVA recorded 23 mass shootings in May 1–23 (1.0/day GVA; ~1.25/day MST equivalent).
• With parameter uncertainty modeled as a mixture of Poisson distributions centered on means of 12–22, P(≥15) ≈ 80%.
• The resolution check on June 15 is 7 days after the window closes, sufficient to capture most incidents given the tracker’s typical 5–7 day reporting lag.

Trajectory 2 reasoning

Reference class: MST mass shootings per 15-day window in late May/early June during a declining-rate year.

• Base rate: MST 2026 YTD = 188 incidents in 143 days = 1.315/day.
• The MST records ~25% more incidents than GVA (188 vs 151 GVA YTD) because MST includes the shooter in the 4-count.
• For a 15-day window at the annual base rate: 15 × 1.315 = 19.7 expected incidents.
• Adjustment +10–15% for summer seasonal peak (June–August are the highest months per GVA decade-long data) and the window opening on Memorial Day (May 25, 2026), historically one of the peak gun-violence days: expected ~22 incidents.
• Even at just the annual base rate of ~20/15 days, P(≥15) is very high.
• Using a negative-binomial model with mean ~22 and SD ~6 (combining Poisson variance with rate uncertainty), P(X ≤ 14) ≈ 10%.
• The 2026 downward trend is already baked into the YTD rate and does not justify a large downward adjustment beyond the base.

Trajectory 3 reasoning

The Mass Shooting Tracker records 188 incidents in 2026 through May 23 (143 days) — a rate of 1.315 incid

Key Uncertainties:

• Whether MST’s reporting lag will leave 1–3 June 7–8 incidents uncaptured by the June 15 snapshot
• Magnitude of Memorial Day weekend uplift on the MST count specifically (historical per-window data not directly retrieved)
• Whether the slight May 2026 slowdown (1.26/day vs 1.315/day YTD) represents a genuine trend or noise
• Whether the June 15 snapshot will be accessible and reflect the canonical data (strict-snapshot assumption)

Evidence Sources (16):

• Mass Shooting Tracker homepage
• Gun Violence Archive 2026 Statistics
• US Mass Shooting Map: 121 so far in 2026 - KCRA
• List of mass shootings in the United States in 2026 - Wikipedia
• There were 408 mass shootings in 2025, the lowest in 5 years
• The Data on Gun Violence in America, Q1 2026 - The Trace
• Everytown - 2025 Gun Violence Year Start Statistics
• List of mass shootings in the United States in 2025 - Wikipedia
• The Trace: Gun Violence by the Numbers in 2025
• Gun Violence Archive: Mass Shootings in 2026
• PBS: Why shootings and violence increase in summer months
• Gun Violence Archive: Past Summary Ledgers
• Wikipedia: List of mass shootings in US in 2024
• Mass Shooting Tracker – 2026 data page
• KMBC – US Mass Shooting Map 2026
• GunSafetyFacts – MST 2025 snapshot

Grounding Facts (passed to reviewers):

1. The Mass Shooting Tracker (massshootingtracker.site) reported 188 US mass shootings in 2026 as of approximately May 23-24, 2026.
2. The Mass Shooting Tracker defines a mass shooting as “a single outburst of violence in which four or more people are shot,”

Draft: 15+: 84.3%, 14: 4.1%, 13: 3.4%, 12: 2.6%, 11: 1.9%

Reviewer Panel:

Reviewer (reasoning)

The draft leans heavily on the YTD daily average and a presumed 10–15% Memorial Day/early‐June uplift without examining whether May’s daily rate has actually declined recently or whether the Mass Shooting Tracker’s reporting lag might leave late‐window incidents unrecorded by June 15. These assumptions anchor the high P(≥15) but rest on shaky, unverified parameters.

Objections:

• The May 2026 daily rate (~1.26/day) appears slightly below the YTD average (1.315/day), suggesting a modest downward drift that the draft ignores.
• Mass Shooting Tracker’s update lag can exceed 7 days for some incidents; assuming full completeness by June 15 risks undercounting.
• The size of the seasonal/holiday spike is assumed rather than backed by per‐year data—10–15% uplift may be overstated.

Reviewer (calibration)

The forecast provides a solid base rate calculation and appropriately incorporates seasonal uplift for Memorial Day and early summer. However, it could benefit from a more explicit quantification of this seasonal effect based on historical data for the specific 15-day window. There’s also a minor inconsistency in framing the 2026 trend relative to 2025, though this doesn’t significantly impact the core YTD rate used.

Objections:

• The quantification of the seasonal uplift for Memorial Day weekend and early June is somewhat vague; a more precise historical analysis of this specific 15-day period’s deviation from the annual average would strengthen the adjustment.
• There is a minor inconsistency in the framing of the 2026 trend, with one trajectory referring to it as a ‘declining-rate year’ while another states the 2026 rate is ‘45% above the same period in 2025.’
• The forecast places a very large proportion of probability (84%) into the ‘15+’ bin, which, while likely correct, offers limited resolution for the actual expected count above 15.

Reviewer (fact-checker)

1 factual error(s). Verdict: minor_issues

Objections:

• [minor] GVA recorded 23 mass shootings in May 1–23 (1.0/day GVA — Corpus says: Corpus states GVA recorded 24 mass shootings from May 1-18 2026 (rate ~1.33/day); no support for exactly 23 incidents May 1-23

Adjustment Rationale:

Adjusted from the trajectory-1 estimate (79.9%) and trajectory-3 estimate (82.9%) up slightly to 82.9%, and moved probability mass from the very-low bins (0–6) into the 9–14 bins to widen the lower tail in response to reviewer 1’s valid concerns about: (a) MST May 2026 rate possibly running slightly below the YTD 1.315/day average (~1.26/day), (b) MST crowd-sourced reporting lag that may exceed 7 days for some incidents, leaving 1–2 June 7–8 incidents potentially uncounted by June 15. I did not move toward reviewer 2’s 90% because reviewer 1’s concerns about lag and May slowdown are evidence-based and partially offset the strong base-rate signal. The fact-checker’s flag (23 vs 24 GVA incidents in different sub-periods) is a minor descriptive error that does not change the MST base rate calculation, which is the actual driver. Central calculation unchanged: 1.315/day × 15 days = 19.7 expected; Memorial Day/early-summer uplift +5–8%; reporting lag –1 to –2 incidents; net central estimate λ ≈ 19. Under Poisson(19) with parameter uncertainty modeled as a mixture (means 14, 17, 20, 23 with weights 0.10, 0.20, 0.50, 0.20), P(X≥15) ≈ 0.83.

forecast_sdk | 615.0s | research $2.5467 + reviewers $0.0114 + reconcile $0.1948 = $2.7889

Extracted Percentile Values: {0.1: 3, 1.0: 6, 5.0: 10, 10.0: 13, 15.0: 15, 20.0: 16, 25.0: 17, 30.0: 18, 35.0: 19, 40.0: 20, 45.0: 20, 46.0: 20, 47.0: 21, 48.0: 21, 49.0: 21, 50.0: 21, 51.0: 22, 52.0: 22, 53.0: 22, 54.0: 23, 55.0: 23, 60.0: 24, 65.0: 25, 70.0: 26, 75.0: 27, 80.0: 29, 85.0: 31, 90.0: 33, 95.0: 38, 99.0: 45, 99.9: 55}

Model’s Answer:

Forecasting Mass Shootings: May 25 – June 8, 2026

Understanding the Question

I need to predict the number of mass shooting incidents the Mass Shooting Tracker will record during a 15-day window (May 25 – June 8, 2026 inclusive), as observed on June 15, 2026.

Key Data Analysis

Current 2026 Pace:

• The Mass Shooting Tracker had recorded 187 incidents through approximately May 22, 2026
• This represents ~142 days into the year = 1.32 incidents/day average
• 2026 is running approximately 45% higher than the same period in 2025

Historical Annual Baselines (MST definition):

• 2024: ~600 incidents → 1.64/day
• 2021 (peak): ~830 incidents → 2.27/day
• 2019: ~417 incidents → 1.14/day

For a 15-day window at current 2026 rates:

• At 1.32/day: ~19.8 incidents expected
• With late-spring seasonality adjustment (+10-15%): ~21-23 incidents

Seasonality Considerations

The May 25 – June 8 window includes:

• Memorial Day weekend (historically associated with elevated incidents)
• Multiple weekend periods with increased social gatherings
• Beginning of summer warmth, which research links to higher firearm violence rates

Uncertainty Factors

Why a LOW outcome could occur:

• Significant reporting lag leaving incidents uncaptured by June 15
• Unusually quiet period (statistical fluctuation)
• Data entry delays for borderline cases (exactly 4 shot)
• Probability: ~15-20%

Why a HIGH outcome could occur:

• 2026’s elevated pace (45% above 2025) continues or accelerates
• Memorial Day weekend creates clustering
• Strong media coverage improves crowd-sourced detection
• Probability: ~20-25%

Critical Assumptions

1. MST’s 2026 daily rate continues near current pace (~1.3-1.5/day) – if the elevated 2026 trend reverses sharply, counts would be lower. Probability of significant reversal: ~15%

2. Reporting completeness by June 15 – incidents occurring near June 8 may not be fully entered by resolution date. Probability of significant data lag: ~20%

3. Seasonality effects as expected – unusual weather or social patterns could shift expected activity. Probability of deviation: ~10%

Distribution Reasoning

Given the data strongly suggests a daily rate of 1.3-1.6 incidents, my central estimate is approximately 20-22 incidents for the 15-day window. The default range maximum of 14.5 appears inconsistent with actual MST historical data, so I’m forecasting well above that range.

The explicit lower bound of 1 requires me to keep all percentiles above 1. Given approximately 1+ incidents occur daily under this definition, fewer than 5 incidents total would require an extraordinary deviation.

My 90% confidence interval spans roughly 12-32, acknowledging:

• Daily variance can cause significant swings
• Reporting lags may reduce captured counts
• The 2026 elevated pace could accelerate further

Percentile .1: 3 Percentile 1: 6 Percentile 5: 10 Percentile 10: 13 Percentile 15: 15 Percentile 20: 16 Percentile 25: 17 Percentile 30: 18 Percentile 35: 19 Percentile 40: 20 Percentile 45: 20 Percentile 46: 20 Percentile 47: 21 Percentile 48: 21 Percentile 49: 21 Percentile 50: 21 Percentile 51: 22 Percentile 52: 22 Percentile 53: 22 Percentile 54: 23 Percentile 55: 23 Percentile 60: 24 Percentile 65: 25 Percentile 70: 26 Percentile 75: 27 Percentile 80: 29 Percentile 85: 31 Percentile 90: 33 Percentile 95: 38 Percentile 99: 45 Percentile 99.9: 55

Forecast Summary

Forecast: No median (P50) available — distribution cannot be finalized due to unresolved methodological disagreement among forecasters.

Rationale

• Historical anchors are strong but sparse: The Mass Shooting Tracker recorded 17 incidents in this calendar window in 2023 and 22 in 2024. These are the only two reliable data points; 2025 data is corrupted by a reporting artifact. All forecasters converge on a central estimate near 20–21 incidents.

• 2026 trajectory mirrors 2024 closely: Through May 23, 2026 has recorded exactly 188 incidents—identical to 2024’s count at the same calendar point. This structural parallel is the strongest single anchor, suggesting the May 25–June 8 window should produce ~22 incidents (2024’s result).

• Seasonal and holiday effects are modest: Memorial Day (May 25) historically elevates gun violence, and June typically runs ~6% above May. However, this effect is already captured in the 2024 comparison. Forecasters weight this at 15–25% of total variance.

• Declining multi-year trend creates downward pressure: Annual MST counts fell from 759 (2023) → 576 (2024) → 488 (2025). The 2026 YTD rate (1.31/day) matches 2025’s full-year pace, suggesting the decline may have stabilized or continued. This argues for an outcome closer to 17–20 rather than 22.

• Reporting lag and data quality introduce uncertainty: The June 15 observation date is 7 days after the window closes. Crowd-sourced reporting may undercount late incidents or, conversely, produce bulk-entry artifacts similar to 2025’s anomaly. This widens confidence intervals but does not shift the central estimate.

• Disagreement on distribution shape prevents consensus: Forecasters agree on a mean near

Forecast (percentiles, aggregated):

• p10: 16.0
• p25: 21.0
• p50: 26.0
• p75: 32.0
• p90: 38.0

Per-model forecasts:

• 1: p10=14, p25=18, p50=24, p75=29, p90=34
• 2: p10=12, p25=13, p50=13.5, p75=14, p90=14.5
• 3: p10=13.5, p25=13.8, p50=14.1, p75=14.3, p90=14.5

Rationale: Summary The expected number of mass shootings between May 25 and June 8, 2026, is driven by the overall incident baseline for the year combined with significant early summer seasonality. The Mass Shooting Tracker employs a broad definition of a mass shooting (four or more people shot), which results in high overall counts. Over the past several years (2022–2025), this specific 15-day window has yielded between 28 and 44 incidents. Through late May 2026, the year-to-date rate is approximately 1.31 incidents per day. This closely mirrors the overall pace of 2025 (1.34 per day), which ended with 488 total incidents—the lowest in recent years. While a raw extrapolation of the 2026 baseline over 15 days suggests around 20 incidents, late spring and early summer historically exhibit a seasonal increase of roughly 40% (a 1.4x multiplier) compared to the annual average. Applying this seasonal adjustment projects approximately 27 incidents. The central estimate of 26 reflects this historically grounded projection, adjusted slightly downward to account for a noticeable lull in mid-May 2026. The distribution is widened to account for the natural clustering of these events.

Strongest Arguments for Higher Values

• Historical precedent for this exact window is very high; the period saw 36 to 37 incidents in 2024, and 44 incidents in both 2022 and 2023.
• The 15-day window begins on Memorial Day (May 25) and includes two full summer weekends. These are periods consistently associated with spikes in outdoor gatherings and gun violence.
• Statistical variance in violent events often leads to clustering, meaning a few concentrated outbreaks could rapidly push the count into the mid-to-high 30s.

Strongest Arguments for Lower Values

• Overall rates of violence have trended downward from their 2022–2024 peaks; 2026 is tracking closely with 2025, which saw 28 incidents during this window.
• A pronounced slowdown occurred just prior to the forecast window, with only 6 incidents recorded between May 16 and May 23, 2026. If this lull persists, the final count could fall into the high teens.
• Because the resolution relies on a crowd-sourced database checked on June 15, any delays or lags in data entry could result in incidents from the end of the window not being counted in time.

Key Uncertainties

• The persistence of the recent mid-May slowdown and whether it represents statistical noise or a meaningful drop in baseline violence.
• The exact magnitude of the early summer seasonal spike, particularly over the high-risk Memorial Day weekend.
• The efficiency of crowd-sourced reporting, specifically whether incidents occurring near the June 8 cutoff will be verified and uploaded by the June 15 resolution date.