TABLE 4.

Choosing the threshold for moderate-to-vigorous intensity physical activity by examining the false positives and false negatives based for approach 2 (eight activities)

Accelerometer (counts·30 s-1)	True Positive (N)	True Negative (N)	False Positive (N)*	False Negative (N)**	Error Rate (%)	Validation Error Rate (%)*** (5th, 95th Percentile)
1100	239	273	43	6	8.7	6.4,11.4
1150	242	273	40	6	8.2	5.9,10.3
1200	252	270	30	9	7.0	4.6, 8.9
1250	259	270	23	9	5.7	3.5, 7.5
1300	263	269	19	10	5.2	3.4, 7.0
1350	268	267	14	12	4.6	2.9, 6.7
1400	269	266	13	13	4.6	3.0, 6.7
1450	274	261	8	18	4.6	3.0, 6.6
1500	276	258	6	21	4.8	2.8, 6.5
1550	277	250	5	29	6.1	4.1, 7.9
1600	279	247	3	32	6.2	3.9, 8.2

^*Counts measured under the protocols for watching TV, playing a computer game, sweeping the floor, and slow walking that were above the threshold for moderate intensity activity were considered as false positives.

^**Counts measured under the protocols for brisk walk, stair walk, shoot baskets, and run that were below the threshold for moderate intensity activity were considered as false negative (exclude step aerobics and bicycling).

^***Based on 100 bootstrap samples, each half the size as the original sample.