HQ BaselineNormative data
What Normative Data Can and Can't Do When You Don't Have a Baseline
When no individual baseline exists, clinicians fall back on population data. Here's when that works — and when it doesn't.
If no individual baseline exists — because the athlete never took one, or the data was lost, or they changed schools — clinicians fall back on population normative data for post-injury comparison. Understanding the strengths and limitations of normative data is important for both clinicians and families.
What normative data is
Normative data consists of average scores (with standard deviations) derived from large populations of healthy, non-concussed individuals, stratified by age and sex, and sometimes by sport or education level. ImPACT maintains a normative database derived from millions of administrations. The CARE Consortium study, published in the American Journal of Sports Medicine (Pandey et al., 2024), found that for the majority of collegiate athletes, normative data performed comparably to individual baselines for concussion detection — a finding that has significant implications for the field.
When normative data works well
For a typical, healthy athlete without complicating factors, normative data provides a reasonable comparison point. If a 16-year-old female soccer player with no medical history sustains a concussion and her post-injury ImPACT scores fall well below the normative range for her age and sex, the clinical conclusion is straightforward regardless of whether she had a personal baseline.
When normative data fails
For athletes whose “normal” falls outside population norms — those with ADHD, learning disabilities, autism spectrum disorder, prior concussions, mood disorders, or migraine history — normative data can be misleading in both directions. Research by Covassin et al. (2017) in the Journal of Athletic Training documented that these preexisting factors significantly influence baseline scores. An athlete with ADHD whose healthy verbal memory score is at the 25th percentile (normal for them, but below average for the population) might be compared to a normative mean at the 50th percentile — masking a genuine post-injury decline.
The practical recommendation
If your athlete has any complicating medical or neurodevelopmental factors, an individual baseline is strongly recommended. If they’re a healthy athlete with no complicating history and a baseline isn’t available, normative data provides a reasonable (though imperfect) alternative. But getting a baseline for next season is still worthwhile.
At Headquarters, we prioritize individual baselines for all athletes but especially for those with complicating factors where normative comparison is least reliable.