2.2. Sample size
unintentional injury
We calculated sample size using a formula for comparing two incidences at a 1:1 ratio (representing the intervention group and control group, respectively); unintentional injury rate was used as the indicator. The formula was:In a previous non-controlled intervention study conducted in China, on-site research focusing on children aged 1–6 years found unintentional injury rates of 23% and 4% before and after the intervention, respectively (