The effect may be statistically significant depending on your tolerance: R> prop.test(c(12, 24), c(5563, 4403)) 2-sample test for equality of proportions

The effect may be statistically significant depending on your tolerance: R> prop.test(c(12, 24), c(5563, 4403)) 2-sample test for equality of proportions with continuity correction data: c(12, 24) out of c(5563, 4403) X-squared = 6.5211, df = 1, p-value = 0.01066 alternative hypothesis: two.sided 95 percent confidence interval: -0.0059903650 -0.0005970741 sample estimates: prop 1 prop 2 0.002157109 0.005450829