| How much monitoring is necessary for stable measures of physical activity and sedentary behaviour? | 3–7 days desirable | 43; number of days and hours per day need to be determined for each setting and application |
| Where should the accelerometer be placed? | Right-hip placement evidence-based, alternative placements need justification and greater evidence | 3 5–9 |
| What activity sampling interval (epoch) should be used? | Lack of evidence | See later in this review; the effect of epoch smaller than is appreciated |
| Which cut-points(s) should be used to convert accelerometry output to physical activity and sedentary behaviour, and to what extent does it matter? | Wide variation in practice; implications of using different cut-points not widely appreciated | See text; critique of existing evidence and new evidence provided |
| How should data be reduced and interpreted ? | Collection of additional information, eg, parent or child log-sheets helpful. Distinct lack of consistency in practice; greater transparency in methods would be helpful | 5–9 |
| Missing data |
| Strings of zeros |
| Are cut-points age dependent? | Lack of empirical evidence in children | New evidence in present text suggests that cut-points are largely independent of age |
| Uniaxial measurement in (vertical plane) | Theoretical advantage to tri-axial accelerometry. Empirical evidence shows no improvement in accuracy with tri-axial systems | 5–9 |
| Or bi-axial (two planes) |
| Or tri-axial accelerometry? (all three planes)? |