highly significantP < 0.0001
Analysis by R, fitting a GLM with a quasibinomial error structure, confirmed the highly significant main effects of age (change in deviance = 84.45, P < 0.0001, for 6 df) and region (change in deviance = 27.03, P < 0.0001, for 3 df), and the 2-way interaction between age and region (change in deviance = 34.85, P = 0.01, for 18 df, residual degrees of freedom = 1615).