Development of a wearable global positioning system for place and health research

Table 3 Resolution estimates of four GPS instruments derived from four transportation modes in three built environment types

Walking Tests
					Fraction of points within each buffer (%)
					Mixed Density				Open Sky				Urban Canyon
GPS ID	N	Sats HDOP		PDOP	N	± 5 m	± 3.5 m	± 2 m	N	± 5 m	± 3.5 m	± 2 m	N	± 5 m	± 3.5 m	± 2 m
6	824	8.9	1.47	3.08	419	91.4	78.5	53.0	189	100.0	98.9	85.7	216	71.3	64.8	52.8
14	821	8.6	1.96	2.70	412	52.4	40.8	27.4	203	95.1	82.8	53.2	206	43.2	35.9	20.9
15	702	9.9	1.43	2.87	355	84.5	73.0	53.8	167	98.8	97.6	87.4	180	62.2	56.1	43.3
23	826	9.1	1.51	3.02	418	87.1	80.1	61.5	189	98.9	94.2	81.0	219	61.2	56.6	41.1
Mean	800	9.2	1.68	2.88	403	74.5	63.2	44.5	190	96.9	90.8	72.0	206	57.0	49.2	35.0
Bicycle Tests
6	294	8.7	1.58	2.61	140	90.0	74.3	47.9	81	100.0	97.5	76.5	73	50.7	34.2	16.4
14	297	9.1	1.52	2.49	141	73.8	58.2	38.3	80	98.8	97.5	87.5	76	53.9	43.4	30.3
15	296	8.2	1.61	2.66	135	78.5	65.9	41.5	81	98.8	91.4	64.2	76	60.5	42.1	25.0
23	293	8.4	1.55	2.53	139	82.0	61.2	38.1	82	98.8	90.2	70.7	72	50.0	41.6	20.8
Mean	295	8.6	1.57	2.57	138	81.0	64.9	41.4	81	99.1	94.1	74.7	74	53.7	40.3	23.1
Automobile Tests
6	454	10.1	1.28	2.69	296	94.3	87.5	69.6	63	92.1	76.2	49.2	95	83.2	69.5	60.0
14	454	9.9	1.27	2.65	296	94.9	83.1	63.9	63	92.1	82.5	55.6	95	84.2	72.6	53.7
15	452	10.1	1.25	2.56	294	78.6	70.1	51.7	63	92.1	82.5	61.9	95	77.9	75.8	58.9
23	454	10.1	1.25	2.59	296	88.2	80.1	56.4	63	92.1	81.0	57.1	95	85.3	74.7	54.7
Mean	454	10.0	1.26	2.62	295	89.0	80.2	60.4	63	92.1	80.5	55.9	95	82.6	73.1	56.8
Transit Bus Tests
6	1076	9.7	1.45	2.46	827	72.8	58.4	37.2					249	73.1	57.0	36.1
14	885	8.8	1.52	2.57	618	60.0	43.9	23.3					267	64.4	50.2	27.3
15	767	7.5	1.31	2.16	552	69.4	55.1	36.2					215	61.9	47.4	31.2
23	929	7.2	1.34	2.24	725	70.5	55.3	37.2					204	62.3	44.6	27.0
Mean	918	8.3	1.41	2.37	680	65.0	50.3	31.6					237	60.2	45.8	28.1

ISSN: 1476-072X