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Table 3 Comparison of the number of significant reliable change rates for each outcome measure among athletes who sustained concussion in the early, mid, and late season

From: Initial symptom presentation after high school football-related concussion varies by time point in a season: an initial investigation

Post-concussion outcome n (%) Early season Midseason Late season χ 2c p value Φ d
Verbal memorya 62 (14.83) 352 (16.94) 26 (26.53) 7.72 0.02
Visual memorya 42 (10.04) 280 (13.47) 16 (16.32) 4.58 0.10
Visual motor speeda 30 (7.18) 224 (10.78) 16 (16.32) 8.67 0.01
Reaction timea 78 (18.66) 440 (21.17) 28 (28.57) 4.79 0.09
Total symptom scorea 64 (15.31) 482 (23.20) 36 (36.73) 24.40 < 0.001 0.1
Number of symptoms increasedb 190 (45.45) 1040 (50.05) 62 (63.27) 10.32 0.006 0.06
  1. Italics indicates significant p value based on Bonferroni-corrected alpha levels = 0.008
  2. aPercentages of athletes classified as concussed based on Reliable change indices at the 80% confidence interval level [44]
  3. bIncrease in number and severity of symptoms based on a previously validated cutoff score (2+ symptoms, increased 1+ point) to classify athletes as meaningfully changed from baseline [45]
  4. cχ 2 analyses comparing the proportion of athletes classified as concussed based on Reliable change indices at the 80% confidence interval level [44]
  5. dPhi effect size interpretation values: [df = 2] small = 0.07, medium = 0.21; large = 0.35
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