Abstract: Objective To review statistics-related problems in the process of obtaining real world evidence (RWE) from real world research (RWS). Methods In regard to real world data (RWD), causal inference methods for RWS and approaches to RWE evaluation were reviewed while the existing problems were analyzed and discussed. Results Obtaining reliable RWE that could be used to support regulatory decisions about medical products was an important goal of RWS. An appropriate standard for RWD data was a prerequisite for quality evaluation of the data. A standardized process of data governance and a perfect system for data quality evaluation underlay high-quality RWS. Standardized implementation of causal inference analytical methods could ensure the quality of RWE. Clinically explicable and innovative conclusions were critical to RWE. Objectivecriteria for evaluation of RWE were also needed in practice. The verifiability of results of RWS was the most important feature of RWE. Conclusion A single clinical trial is often unable to meet the criteria for determining causality. Instead, multiple studies are required to verify causality from different perspectives. Therefore, the combination of randomized controlled trials (RCT) and RWS is a good approach during drug development.

Key words: real world study, real world data, real world evidence, causal inference, data quality