Longitudinal data in biomedical studies often involve concomitant interventions in addition to the pre-specified repeatedly measured outcome and covariate variables. Since a concomitant intervention ...

This is a preview. Log in through your library . Abstract Multilevel modelling is a popular approach for longitudinal data analysis. Statistical models conventionally target a parameter at the centre ...

A behind-the-scenes blog about research methods at Pew Research Center. For our latest findings, visit pewresearch.org. Identifying causal relationships from observational data is not easy. Still, ...