Trial sequential analysis: A simple guide for judging the conclusiveness of the effect.

Meta-analysis is a statistical method used in systematic reviews to provide a quantitative estimate of the effect. However, including very few studies and participants may increase the risk of spurious findings. Trial sequential analysis (TSA) has been introduced to enhance the robustness of meta-analysis. TSA is a cumulative meta-analysis method that weighs type I and II errors while estimating the effect. The application of TSA can lead to a more accurate estimation of the clinical effectiveness of the intervention. The aim of the present paper was to introduce the TSA to orthodontic clinicians and researchers using continuous data from an orthodontic systematic review.