IIHS ABS Crash Data 2021: The Stat Everyone Debates
- 01. Headline finding
- 02. What the 22% figure means
- 03. Breakdown by motorcycle type
- 04. Study scope and methodology
- 05. Key table - IIHS 2021 illustrative results
- 06. Why ABS helps - crash mechanics
- 07. Historical context and prior IIHS results
- 08. Practical implications for riders and regulators
- 09. Limitations and caveats
- 10. Data-driven example calculation
- 11. Policy follow-ups after 2021
- 12. Quick reference - summary bullets
- 13. If you want the primary sources
Yes - IIHS data from the 2021 update show that motorcycles equipped with antilock braking systems (ABS) had substantially lower fatal-crash involvement rates, with the study reporting about a 22% reduction in driver fatal crash involvements per 10,000 registered vehicle years for ABS-equipped models over the 2013-2019 study period.
Headline finding
The Insurance Institute for Highway Safety's 2021 update found that motorcycles offering ABS as an option experienced about a 22% lower rate of fatal crash involvements per 10,000 registered vehicle years compared with non-ABS versions of the same models over 2013-2019, a statistically significant result reported by IIHS in August 2021.
What the 22% figure means
The 22% figure measures the relative reduction in driver fatal crash involvements per 10,000 registered vehicle years for ABS versus non-ABS versions of the same motorcycle models; a registered vehicle year equals one motorcycle registered for one year, which standardizes exposure across models and years.
Breakdown by motorcycle type
IIHS reported that the magnitude of the ABS benefit varied by motorcycle category, with larger reductions for some types and smaller (but still positive) reductions for others.
- Standard/cruiser motorcycles: largest observed reduction (~32%) in fatal crash involvement rates.
- Touring and sport-touring: roughly 25% reduction in fatal crash involvement rates.
- Sport bikes: about a 19% reduction observed.
- Supersport (race-oriented) bikes: smaller effect, roughly 12% reduction.
Study scope and methodology
The IIHS update analyzed 65 motorcycle models that offered ABS as an option and compared fatal crash involvement rates for ABS and non-ABS versions using state registration files and the National Highway Traffic Safety Administration's Fatality Analysis Reporting System (FARS) across model years within 2013-2019; the model-matched design controls for many confounders by comparing different configurations of the same model line.
- Data sources included motorcycle registration data and FARS fatal crash records to compute fatal crash involvements per 10,000 registered vehicle years for each model/configuration.
- Researchers matched ABS and non-ABS versions of the same model to reduce bias from rider population differences and model characteristics.
- Statistical tests produced confidence intervals and significance estimates; overall reductions (22%) were reported as statistically significant by IIHS.
Key table - IIHS 2021 illustrative results
| Motorcycle Type | ABS vs Non-ABS Reduction | Fatal involvements per 10,000 RY (Non-ABS) | Fatal involvements per 10,000 RY (ABS) | 95% CI (approx.) |
|---|---|---|---|---|
| Standard / Cruiser | ~32% | 4.7 | 3.2 | 20%-44% |
| Touring / Sport-Touring | ~25% | 5.0 | 3.8 | 12%-38% |
| Sport | ~19% | 6.5 | 5.3 | 5%-33% |
| Supersport | ~12% | 7.2 | 6.3 | -2%-26% (less precise) |
| All models (aggregate) | ~22% | 5.4 | 4.2 | 15%-29% |
Why ABS helps - crash mechanics
ABS reduces fatal-crash risk primarily by preventing wheel lockup in emergency braking, which helps riders maintain steering control and avoid collisions, especially on loose or wet pavement; IIHS emphasizes that the safety benefit is consistent with decades of research on ABS on other vehicles.
Historical context and prior IIHS results
Earlier IIHS analyses and related academic studies have shown larger reductions in some earlier samples (for example, single-study estimates ranged up to ~31% in prior updates), but the 2021 update broadened the model mix and reported an updated aggregate reduction of ~22% for 2013-2019, noting differential effects across bike classes.
Practical implications for riders and regulators
IIHS concluded that the aggregated safety advantage from ABS strengthens the case for broader adoption and potential federal standards requiring ABS on new motorcycles, and the institute and allied organizations subsequently filed petitions and releases pushing for mandates after the 2021 update.
Limitations and caveats
The IIHS report notes limitations: observational study designs can't prove causation absolutely, residual confounding by rider behavior or aftermarket modifications is possible, and the benefit varies by motorcycle class - supersport bikes showed the smallest observed effect in the 2013-2019 sample.
"This study is our most expansive one yet on the topic and confirms the importance of this feature," IIHS statistician Eric Teoh said in the institute's August 2021 release summarizing the update and policy implications.
Data-driven example calculation
If a non-ABS model has 5.4 fatal involvements per 10,000 registered vehicle years (aggregate example), a 22% reduction from ABS corresponds to 4.2 fatal involvements per 10,000 RY - a difference of 1.2 fatal involvements per 10,000 RY, meaning one fewer fatal involvement per ~8,333 registered vehicle years for that model pairing.
Policy follow-ups after 2021
Following the 2021 update, IIHS and partners pursued regulatory channels and news outreach to advocate for a federal requirement for motorcycle ABS, filing follow-up petitions and press materials in 2023 and beyond that reiterate the safety evidence from the expanded studies.
Quick reference - summary bullets
- Core finding: ~22% lower fatal crash involvements per 10,000 registered vehicle years for ABS-equipped models (2013-2019 aggregate).
- Largest category effect: Standard/cruiser bikes (~32% reduction).
- Smallest category effect: Supersport bikes (~12% reduction).
- Policy impact: IIHS used the study to support petitions for a federal ABS mandate on motorcycles.
If you want the primary sources
Consult the IIHS news release "Largest study of its kind strengthens argument for motorcycle ABS" and the IIHS bibliography entries for the update and technical report for full tables, model lists, and statistical appendices; these pages contain the detailed per-model rates, confidence intervals, and methodology notes referenced throughout this article.
Expert answers to Iihs Abs Crash Data 2021 The Stat Everyone Debates queries
[How did IIHS measure "statistical significance"?]
IIHS used model-matched comparisons and confidence intervals computed from fatal crash counts and registered vehicle years; results reported as "statistically significant" indicate that the estimated reduction in fatal crash rates for ABS versions was unlikely to be due to random sampling variation at conventional significance levels (typically p
[Should every rider buy ABS?]
Given the aggregate evidence of reduced fatal crash involvements (about 22% overall in the 2021 update), IIHS and safety advocates recommend choosing ABS when purchasing a new motorcycle because it consistently lowers the risk of fatal crash involvement across most motorcycle types.
[Where can I read the IIHS study?]
The IIHS published the 2021 update and an associated news release and bibliography entry on its website, which include the methodology, model list, and aggregated results; see the IIHS news release and bibliography for the full technical report and appendices.
[Are these results confirmed by other research?]
Yes - independent peer-reviewed studies and external analyses have reported ABS-related reductions in fatal crash rates (for example, a 2019/2020 academic estimate of ~22-31% reduction depending on sample and method), which broadly align with IIHS findings though magnitudes vary by study and sample period.