Fig. 4From: Meta-analysis with zero-event studies: a comparative study with application to COVID-19 dataMeta-analyses of COVID-19 data without the double-zero-event studies by applying the Haldane estimator (top), the TACC estimator (middle), and the hybrid estimator (bottom). COVID-19: Coronavirus disease 2019, TACC: Treatment arm continuity correction, RR: Relative risk, CI: Confidence intervalBack to article page