Statistical analysis
empyema, volume reduction
CAVITY, EMPYEMA
Statistical analysis was performed using IBM SPSS ver. 24 (Armonk, NY, USA). The Shapiro–Wilk test was used to test for the normality of distribution. Continuous variables with normal distribution are reported as mean ± standard deviation (SD), and non-normal variables are reported as median + interquartile range. To compare the preoperative and postoperative volume of the empyema cavity, the Wilcoxon matched pair signed rank test was used. A comparison between the volume reduction in this study and that of Nishi et. alA 