Refining Time-Activity Classification of Human Subjects Using the Global Positioning System
文献类型：SCI/SSCI论文
| 作者 | Hu M. G.; Li, W.; Li, L. F.; Houston, D.; Wu, J. |
| 发表日期 | 2016 |
| 关键词 | random forests physical-activity air-pollution accelerometer data ultrafine particles gps tracking los-angeles exposure travel location |
| 英文摘要 | Background Detailed spatial location information is important in accurately estimating personal exposure to air pollution. Global Position System (GPS) has been widely used in tracking personal paths and activities. Previous researchers have developed time-activity classification models based on GPS data, most of them were developed for specific regions. An adaptive model for time-location classification can be widely applied to air pollution studies that use GPS to track individual level time-activity patterns. Methods Time-activity data were collected for seven days using GPS loggers and accelerometers from thirteen adult participants from Southern California under free living conditions. We developed an automated model based on random forests to classify major time-activity patterns (i.e. indoor, outdoor-static, outdoor-walking, and in-vehicle travel). Sensitivity analysis was conducted to examine the contribution of the accelerometer data and the supplemental spatial data (i.e. roadway and tax parcel data) to the accuracy of time-activity classification. Our model was evaluated using both leave-one-fold-out and leave-one-subject-out methods. Results Maximum speeds in averaging time intervals of 7 and 5 minutes, and distance to primary highways with limited access were found to be the three most important variables in the classification model. Leave-one-fold-out cross-validation showed an overall accuracy of 99.71%. Sensitivities varied from 84.62% (outdoor walking) to 99.90% (indoor). Specificities varied from 96.33% (indoor) to 99.98% (outdoor static). The exclusion of accelerometer and ambient light sensor variables caused a slight loss in sensitivity for outdoor walking, but little loss in overall accuracy. However, leave-one-subject-out cross-validation showed considerable loss in sensitivity for outdoor static and outdoor walking conditions. Conclusions The random forests classification model can achieve high accuracy for the four major time-activity categories. The model also performed well with just GPS, road and tax parcel data. However, caution is warranted when generalizing the model developed from a small number of subjects to other populations. |
| 出处 | Plos One |
| 卷 | 11 |
| 期 | 2 |
| 语种 | 英语 |
| ISSN号 | 1932-6203 |
| DOI标识 | 10.1371/journal.pone.0148875 |
| 源URL | [http://ir.igsnrr.ac.cn/handle/311030/42985]  |
| 专题 | 地理科学与资源研究所_历年回溯文献 |
| 推荐引用方式 GB/T 7714 | Hu M. G.,Li, W.,Li, L. F.,et al. Refining Time-Activity Classification of Human Subjects Using the Global Positioning System. 2016. |
入库方式： OAI收割
来源：地理科学与资源研究所
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