Comparison of Three Inexpensive Commercially Available Activity Monitors to a Previously Validated Tri-Axial Accelerometer
Bibliographic record
Abstract
Inexpensive personal activity monitors have recently gained popularity with the general public. Given the current wide-spread use of these devices, it is important to ensure that users are attaining accurate information compared to previously validated measures. PURPOSE: To compare the accuracy of the Fitbit Force™ and One™ activity monitors in measuring steps per day and time spent in different intensities of activity with the ActiGraph GT3X™tri-axial accelerometer. METHODS: Twenty-two women, 18-26y.o. with a BMI of 23.24 ± 3.26kg/m2 wore two Fitbit Ones TM (Bra and Waist respectively), a Fitbit Force TM (Wrist), and an ActiGraph GT3X™(Waist) for 7-consecutive days. ActiGraph™ data was processed using Actilife™ V5.1.1 and the Freedson equation activity cut points. Fitbit™ data was processed using their proprietary online software. A multivariate analysis of variance (MANOVA) was used to compare steps per day and time spent in light, moderate and vigorous intensity activities between the four devices. A post-hoc test of the least squared difference was used to determine where any differences occurred RESULTS: The activity monitors differed in time spent in light F(3,19)= 3.16, p>.05) and vigorous (F(3,19)= 3.16, p>.05) intensity activities. Post-hoc comparisons revealed that the GT3X™ differed from all three Fitbit™ devices in the measurement of time spent in light (GT3X= 89.92±36 min, Force=419.97±129.22 min, Bra=379.93±122.2 min, Waist=392.75±114.78 min) and vigorous activities (GT3X=7.05±9.63 min, Force=36.91±27.7 min, Bra=31.29±18.53 min, Waist=30.45±18.3 min). There was no difference found in the number of steps per day or minutes of moderate intensity activity recorded between the four devices. CONCLUSIONS: Fitbit™ activity monitors compare well to other previously validated objective activity monitors in the measurement of steps per day and time spent in moderate intensity activities. However, Fitbit™ devices may not accurately quantify the time spent in light and vigorous intensity activities, and therefore may not be the ideal solution for individuals’ personal activity monitoring needs.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.003 | 0.007 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".