Community health centers (CHCs) in Ethiopia play a crucial role in providing primary healthcare services to rural and underserved populations. The reliability of these systems is essential for ensuring effective service delivery, but there is limited evidence on how CHC systems can be reliably evaluated. A Difference-in-Differences model was employed to analyse pre- and post-intervention data from CHCs across different regions in Ethiopia. Data on patient flow, resource allocation, and staff performance were collected using a standardised questionnaire. Robust standard errors were used to account for potential heterogeneity. The analysis revealed significant improvements in patient wait times and resource utilization post-intervention, with a reduction of approximately 20% in average waiting periods (mean = 35 minutes). The DiD model demonstrated high reliability and validity in measuring system changes over time. The findings suggest that CHCs can be effectively monitored for service improvements. Future research should consider longitudinal data collection to further validate the DiD methodology's applicability and reliability across different settings. community health centers, Ethiopia, Difference-in-Differences, healthcare systems evaluation, robust standard errors