The paper discussed the overall aspects of systematic review and meta-analysis and explored the main mathematical context of meta-analysis. This included various methods of analyzing the effect size and obtaining the average effect size depending on the variable type. In doing so, methods of obtaining effect sizes in continuous outcome variables, categorical outcome variables, and correlation coefficients in studies were reviewed. In order to average the effect size, a fixed-effect model and a random effect model can be used. Finally, a forest plot can be drawn to visualize and interpret the results. Through this series of processes, researchers will be able to develop a better understanding of the systematic review and meta-analysis and perform a meta-analysis of their own.