Table 4.
Wrist and ankle classification confusion matrices for the four target activity groups using the SVM classifier with LOSO cross-validation. Correct classifications are in bold.
| Part A, experiment 1, original feature set, Youth dataset | |||||
|---|---|---|---|---|---|
| Wrist | Ambulation | Cycling | Other activities | Sedentary | |
| Ambulation | 646 (75.6%) | 26 (3%) | 52 (6.1%) | 131 (15.3%) | |
| Cycling | 26 (2.1%) | 1067 (87.5%) | 36 (3%) | 90 (7.4%) | |
| Actual label | Other activities | 38 (3%) | 38 (3%) | 1038 (81.7%) | 157 (12.4%) |
| Sedentary | 16 (0.6%) | 44 (1.8%) | 170 (6.8%) | 2277 (90.8%) | |
| Overall accuracy 85.9 % | |||||
| Ankle | Ambulation | Cycling | Other activities | Sedentary | |
| Ambulation | 752 (88%) | 41 (4.8%) | 60 (7%) | 2 (0.2%) | |
| Cycling | 24 (2%) | 1074 (88%) | 89 (7.3%) | 33 (2.7%) | |
| Actual label | Other activities | 50 (3.9%) | 58 (4.6%) | 1025 (80.5%) | 140 (11%) |
| Sedentary | 1 (0%) | 16 (0.6%) | 94 (3.7%) | 2433 (95.6%) | |
| Overall accuracy 89.7 % | |||||
| Part B, experiment 2, new feature set, Youth dataset | |||||
| Wrist | Ambulation | Cycling | Other activities | Sedentary | |
| Ambulation | 674 (78.8%) | 39 (4.6%) | 60 (7%) | 82 (9.6%) | |
| Cycling | 14 (1.1%) | 1104 (90.6%) | 21 (1.7%) | 80 (6.6%) | |
| Actual label | Other activities | 36 (2.8%) | 11 (0.9%) | 1149 (90.4%) | 75 (5.9%) |
| Sedentary | 8 (0.3%) | 35 (1.4%) | 63 (2.5%) | 2401 (95.8%) | |
| Overall accuracy 91.0 % | |||||
| Ankle | Ambulation | Cycling | Other activities | Sedentary | |
| Ambulation | 818 (95.7%) | 10 (1.2%) | 27 (3.2%) | 0 (0%) | |
| Cycling | 7 (0.6%) | 1101 (90.2%) | 79 (6.5%) | 33 (2.7%) | |
| Actual label | Other activities | 35 (2.7%) | 19 (1.5%) | 1084 (85.2%) | 135 (10.6%) |
| Sedentary | 0 (0%) | 7 (0.3%) | 99 (3.9%) | 2438 (95.8%) | |
| Overall accuracy 92.4 % | |||||
| Part C, experiment 4, new feature set, Youth +Adult dataset | |||||
| Wrist | Ambulation | Cycling | Other activities | Sedentary | |
| Ambulation | 2842 (86.4%) | 149 (4.5%) | 170 (5.2%) | 127 (3.9%) | |
| Cycling | 92 (4.1%) | 1741 (77.3%) | 36 (1.6%) | 383 (17%) | |
| Actual label | Other activities | 85 (3.8%) | 37 (1.7%) | 1943 (87.4%) | 159 (7.1%) |
| Sedentary | 15 (0.3%) | 153 (2.8%) | 124 (2.3%) | 5197 (94.7%) | |
| Overall accuracy 88.5 % | |||||
| Ankle | Ambulation | Cycling | Other activities | Sedentary | |
| Ambulation | 3278 (97.9%) | 31 (0.9%) | 37 (1.1%) | 2 (0.1%) | |
| Cycling | 24 (1.1%) | 2026 (89.7%) | 111 (4.9%) | 97 (4.3%) | |
| Actual label | Other activities | 54 (2.4%) | 29 (1.3%) | 1766 (78.3%) | 407 (18%) |
| Sedentary | 0 (0%) | 16 (0.3%) | 315 (5.7%) | 5211 (94%) | |
| Overall accuracy 91.6% | |||||