COUNT: 310 MAIN WORD COUNT: 4066 *Members are listed at the end of this article.

Background Determining the sample size is a vital aspect of randomised control trial design; typically a (target) difference is specified. This provides reassurance that the study will be informative; i.e. should such a difference exist, it is likely to be detected with the required statistical precision. From both a scientific and ethical standpoint, selecting an appropriate target difference ...

Structured summary2 Provide a structured summary including, as applicable: background; objectives; data sources; study eligibility criteria,participants, and interventions; study appraisal and synthesis methods; results; limitations; conclusions andimplications of key findings; systematic review registration number.2

Purpose A growing body of evidence shows that mindfulness-based interventions reduce symptoms and improve healthrelated quality of life. Several instruments have been developed to measure mindfulness. To make a reasonable choice among these instruments, it is important to know the quality of each instrument. The objectives of this study were to critically assess and compare the measurement prop...