Table 3.
Leave-one-out heat stress classification performance on PPG-chemical, biological and radiological (CBR) responders in the tropical condition database. Four classification methods are used in this analysis: linear discriminant analysis, quadratic discriminant analysis and the linear support vector machine. The PPG signals were collected from 40 heat acclimatized emergency responders for 20 s during the 10-minute break of each exercise (cf. Figure 1). To evaluate the performance of each feature, we applied the score, which is defined as . Here, OA stands for overall accuracy (average of scores for all classifiers). The highest OA of each feature is highlighted.
| Energy-Unfiltered | Entropy-Unfiltered | Energy-Filtered | Entropy-Filtered | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Order | (BE vs. E1) | (BE vs. E2) | (BE vs. E3) | OA | (BE vs. E1) | (BE vs. E2) | (BE vs. E3) | OA | (BE vs. E1) | (BE vs. E2) | (BE vs. E3) | OA | (BE vs. E1) | (BE vs. E2) | (BE vs. E3) | OA |
| 0 | 63.8 | 51.3 | 63.3 | 59.5 | 56.1 | 66.1 | 51.2 | 57.8 | 66.3 | 60.1 | 67.2 | 64.6 | 58.6 | 67.8 | 60.9 | 62.4 |
| 1 | 40.3 | 50.6 | 65.8 | 52.2 | 66.6 | 54.6 | 55.2 | 58.8 | 71.1 | 71.0 | 47.3 | 63.1 | 52.4 | 71.2 | 70.0 | 64.5 |
| 2 | 80.8 | 83.1 | 68.8 | 77.6 | 67.8 | 86.7 | 87.4 | 80.6 | 73.5 | 73.7 | 86.4 | 77.8 | 87.6 | 74.0 | 73.9 | 78.5 |
| 3 | 80.8 | 82.6 | 69.2 | 77.6 | 69.3 | 87.0 | 87.4 | 81.2 | 75.1 | 74.6 | 86.3 | 78.7 | 87.6 | 73.7 | 74.1 | 78.5 |
| 4 | 80.3 | 83.5 | 70.8 | 78.2 | 70.0 | 86.4 | 88.0 | 81.5 | 76.1 | 75.7 | 85.5 | 79.1 | 87.3 | 74.2 | 73.7 | 78.4 |
| 5 | 78.8 | 82.2 | 50.7 | 70.6 | 51.8 | 85.3 | 86.7 | 74.6 | 58.5 | 60.0 | 84.2 | 67.6 | 85.9 | 53.6 | 54.3 | 64.6 |
| 6 | 77.8 | 80.2 | 79.2 | 79.1 | 80.0 | 82.5 | 84.8 | 82.4 | 81.5 | 81.7 | 83.5 | 82.2 | 85.8 | 84.0 | 84.3 | 84.7 |
| 7 | 77.4 | 80.1 | 79.5 | 79.0 | 80.4 | 79.1 | 81.2 | 80.2 | 85.9 | 86.4 | 82.0 | 84.8 | 85.2 | 86.7 | 86.8 | 86.2 |
| 8 | 75.6 | 77.5 | 80.8 | 78.0 | 81.3 | 74.5 | 76.2 | 77.3 | 86.1 | 86.1 | 78.2 | 83.5 | 79.7 | 87.1 | 87.4 | 84.7 |
| 9 | 73.5 | 75.8 | 80.8 | 76.7 | 81.3 | 69.8 | 69.8 | 73.6 | 86.1 | 86.1 | 72.4 | 81.6 | 73.6 | 87.7 | 88.0 | 83.1 |
| 10 | 69.5 | 69.6 | 80.8 | 73.3 | 81.3 | 60.8 | 62.6 | 68.2 | 86.1 | 86.1 | 66.0 | 79.4 | 68.4 | 87.7 | 88.0 | 81.4 |
| 11 | 64.1 | 65.3 | 80.8 | 70.1 | 81.3 | 52.1 | 55.6 | 63.0 | 86.1 | 86.1 | 58.4 | 76.9 | 63.9 | 87.7 | 88.0 | 79.9 |
| 12 | 56.3 | 57.3 | 80.8 | 64.8 | 81.3 | 45.1 | 44.4 | 56.9 | 86.1 | 86.1 | 53.1 | 75.1 | 50.0 | 87.7 | 88.0 | 75.2 |
| 13 | 55.6 | 52.8 | 80.8 | 63.1 | 81.3 | 38.6 | 14.4 | 44.8 | 86.1 | 86.1 | 49.7 | 74.0 | 47.0 | 87.7 | 88.0 | 74.2 |
| 14 | 50.0 | 49.5 | 80.8 | 60.1 | 81.3 | 55.9 | 55.9 | 64.4 | 86.1 | 86.1 | 45.4 | 72.5 | 46.0 | 87.7 | 88.0 | 73.9 |
| 15 | 49.2 | 48.6 | 80.8 | 59.5 | 81.3 | 58.1 | 56.9 | 65.4 | 86.1 | 86.1 | 49.9 | 74.1 | 31.4 | 87.7 | 88.0 | 69.0 |
| 16 | 47.2 | 46.4 | 80.8 | 58.1 | 81.3 | 58.1 | 57.5 | 65.6 | 86.1 | 86.1 | 55.4 | 75.9 | 55.2 | 87.7 | 88.0 | 77.0 |
| 17 | 40.5 | 35.6 | 80.8 | 52.3 | 81.3 | 57.4 | 57.5 | 65.4 | 86.1 | 86.1 | 54.8 | 75.7 | 54.8 | 87.7 | 88.0 | 76.8 |
| 18 | 31.9 | 34.7 | 80.8 | 49.1 | 81.3 | 57.6 | 57.5 | 65.5 | 86.1 | 86.1 | 54.2 | 75.5 | 54.4 | 87.7 | 88.5 | 76.9 |
| 19 | 32.3 | 37.2 | 80.8 | 50.1 | 81.3 | 58.0 | 58.0 | 65.7 | 86.1 | 86.4 | 53.0 | 75.2 | 54.4 | 87.1 | 88.2 | 76.6 |
| 20 | 39.8 | 39.0 | 80.8 | 53.2 | 81.3 | 58.6 | 58.6 | 66.2 | 86.7 | 86.7 | 53.0 | 75.5 | 53.0 | 86.3 | 87.6 | 75.6 |