Individual participant data (IPD) meta-analysis projects obtain, harmonise, and synthesise original data from multiple studies. Many IPD meta-analyses of randomised trials are initiated to identify treatment effect modifiers at the individual level, thus requiring statistical modelling of interactions between treatment effect and participant-level…

Outputs from living evidence syntheses projects have been used widely during the pandemic by guideline developers to form evidence-based recommendations. However, the needs of different stakeholders cannot be accommodated by solely providing pre-defined non amendable numerical summaries. Stakeholders also need to understand the data and perform…

Randomized controlled trials are a special case of designs using an unbiased instrument to take care of confounders even if they are unmeasured or unknown. Another example of studies using instrumental variables is the Mendelian experiment and Directed Acyclic Graphs show the power of such designs to enhance the internal validity. It is argued…

This paper examines the insistent claims by advocates of evidence-based teaching that it is a rigorous scientific approach. The paper questions the view that randomised controlled trials and meta-analyses are the only truly scientific methods in educational research. It suggests these claims are often based on a rhetorical appeal which relies on…

Meta-ethnography and systematic review of qualitative research are needed but also challenged by the link to the evidence movement's models and PISA-traditions for measuring learning effects. For reflections on the perspective for meta-ethnography it means to reconstruct the methodological argument almost divided in a "Before and After…

Most evaluators have embraced the goal of evidence-based practice (EBP). Yet, many have criticized EBP review systems that prioritize randomized control trials and use various criteria to limit the studies examined. They suggest this could produce policy recommendations based on small, unrepresentative segments of the literature and recommend a…

When cluster randomized experiments are analyzed as if units were independent, test statistics for treatment effects can be anticonservative. Hedges proposed a correction for such tests by scaling them to control their Type I error rate. This article generalizes the Hedges correction from a posttest-only experimental design to more common designs…