All analyses were performed using the xtmixed command in STATA IC version 11.
All models are run using the xtmixed command in Stata 11.
A multi-level mixed effect linear regression model was applied using STATA (version 12.0) using the xtmixed command to fit linear mixed models for pedometer steps and distance per minute, enjoyment of PA, enjoyment of lunchtime play activities and QOL.
This is implemented in Stata using the xtmixed command, in SAS with PROC MIXED, and in R with the nlme or lme4 packages (for examples in Stata, see additional file 2: Stata-programs.pdf).pdf
A multi-level mixed effect linear regression model was applied in STATA (version 12.0) using the xtmixed command to fit linear mixed models to each of the variables to examine whether there was a significant difference (p < 0.05) between the intervention and control school at the three time points (pre, post and follow-up).
A weighted multilevel linear regression analysis (a random intercept model) was performed using the xtmixed function in Stata 12.1 software (StataCorp, College Station, TX, USA).
A multilevel linear regression model (using the xtmixed option from STATA 12.1), taking into account the hierarchical structure of the data was used to assess the relationship between BMC, BMD and BA accretion and the categories of physical activity intensity levels.
Data were analysed using multilevel mixed effects linear regression, with two crossed independent random effects accounting for random variation between observers and participants using the xtmixed procedure in Stata 9.2.
These models were fitted using the 'xtmixed' command in Stata (StataCorp LP, College Station, TX, USA) and included adjustment for age and sex.
Modelling was carried out in STATA version 11 and used maximum likelihood estimation within the xtmixed command.
