Randomization and masking
BLIND
We matched the townships (n = 8) into pairs based on the order of the socioeconomic index (per capita disposable income in 2018). Each township was marked as A1, A2, B1, B2, C1, C2, D1, and D2 after four pairs were decided. We used IBM SPSS V.24.0 (IBM Corp) to randomly choose one number in each pair as the intervention township, after which its paired township automatically became a control group. We assigned all the children living in intervention/control townships to the intervention/control groups. We could not blind the participants and facilitators due to the nature of the Care Group intervention.