Inverse probability weighting for causal inference in hierarchical data. - Hu, Lin; Yu, Jie; Yang, Chunxia; Chen, Miaoshuang; Tang, Zihuan; Liao, Rujun; Jike, Chunnong; Wang, Ju; Wang, Ruobing; Liao, Qiang; Zhang, Tao (BMC Medical Research Methodology, 2025)