Kim Taehyun, Lee Kiyoung, Yang Wonho, Yu Seung Do
Seoul National University Environmental Health, 1 Gwanak-ro Gwanak-gu, Seoul 151-742, Republic of Korea.
J Environ Monit. 2012 Aug;14(8):2270-4. doi: 10.1039/c2em30190c. Epub 2012 Jun 27.
Although the global positioning system (GPS) has been suggested as an alternative way to determine time-location patterns, its use has been limited. The purpose of this study was to evaluate a new analytical method of classifying time-location data obtained by GPS. A field technician carried a GPS device while simulating various scripted activities and recorded all movements by the second in an activity diary. The GPS device recorded geological data once every 15 s. The daily monitoring was repeated 18 times. The time-location data obtained by the GPS were compared with the activity diary to determine selection criteria for the classification of the GPS data. The GPS data were classified into four microenvironments (residential indoors, other indoors, transit, and walking outdoors); the selection criteria used were used number of satellites (used-NSAT), speed, and distance from residence. The GPS data were classified as indoors when the used-NSAT was below 9. Data classified as indoors were further classified as residential indoors when the distance from the residence was less than 40 m; otherwise, they were classified as other indoors. Data classified as outdoors were further classified as being in transit when the speed exceeded 2.5 m s(-1); otherwise, they were classified as walking outdoors. The average simple percentage agreement between the time-location classifications and the activity diary was 84.3 ± 12.4%, and the kappa coefficient was 0.71. The average differences between the time diary and the GPS results were 1.6 ± 2.3 h for the time spent in residential indoors, 0.9 ± 1.7 h for the time spent in other indoors, 0.4 ± 0.4 h for the time spent in transit, and 0.8 ± 0.5 h for the time spent walking outdoors. This method can be used to determine time-activity patterns in exposure-science studies.
尽管全球定位系统（GPS）已被提议作为确定时间-地点模式的一种替代方法，但其应用一直受到限制。本研究的目的是评估一种对通过GPS获得的时间-地点数据进行分类的新分析方法。一名现场技术人员在模拟各种预设活动时携带GPS设备，并在活动日志中按秒记录所有动作。GPS设备每15秒记录一次地理数据。每日监测重复进行18次。将通过GPS获得的时间-地点数据与活动日志进行比较，以确定GPS数据分类的选择标准。GPS数据被分为四个微环境（室内居住、其他室内、出行和户外行走）；所使用的选择标准是卫星使用数量（used-NSAT）、速度以及与住所的距离。当used-NSAT低于9时，GPS数据被分类为室内。当与住所的距离小于40米时，分类为室内的数据进一步被分类为室内居住；否则，它们被分类为其他室内。当速度超过2.5米/秒时，分类为户外的数据进一步被分类为出行；否则，它们被分类为户外行走。时间-地点分类与活动日志之间的平均简单百分比一致性为84.3±12.4%，kappa系数为0.71。时间日志与GPS结果之间的平均差异为：在室内居住花费的时间为1.6±2.3小时，在其他室内花费的时间为0.9±1.7小时，在出行花费的时间为0.4±0.4小时，在户外行走花费的时间为0.8±0.5小时。这种方法可用于确定暴露科学研究中的时间-活动模式。
