Table 3 Key practical considerations and implications for study design

School considerations (from Study 1)

Must work around school terms

Minimum measurement period is one school term

1

No more than one measurement per term

Intervention to start at beginning of a term

Steps occur at beginning of term - a maximum number of 6 steps per school year

1

One term needed to implement

Implementation period required of 1 term– requires incomplete design, and reduces maximum number of steps by one

1

Maximum of 4–5 measurement points per school year (3–4 preferable)

Restricts total number of measurements per school per year– may require incomplete design

1

School disruptions at certain times of year (e.g. end of term, Christmas, exam period)

Ideally avoid designs with more schools during busy times

2

Statistical and Logistical considerations

Seasonality in physical activity outcomes

Need to ensure time is modelled correctly, and consider the impact of time on the design

1

Baseline data collection is more intensive

Spread baseline data collection over two terms

Keep data collection spread over time periods

2

Difficulties in managing large volumes of data collection at any time

Class sizes give an upper limit on pupil numbers per school

Allow pupils to join and drop out at different times to maximise participant numbers - open cohort design

2