Adequate statistical tools and their proper application enable reliable assessment of the safety and effectiveness of the tested drugs. To date, several statistical methods have been described that help assess the magnitude of differences between two or more interventions in clinical trials and that provide a better estimate of treatment effects. Medical and biomedical sciences have become fields intensively using research data. It shows the importance of statistical knowledge and the ability to use it in the field of medical/biomedical research. It is the clinician’s responsibility to choose the appropriate method to perform statistical analysis of the tests they have carried out. This article describes and explains SMD statistical methods (standardized mean difference – SMD) and LSMD (least squares mean difference) for comparing the effectiveness of interventions in comparative drug trials.