Table 3.

Parameter estimation for secular trends and seasonality of omphalocele in each region/residential area of China

Model	Variable	Estimate	Standard error	Wald 95% confidence limits		Wald chi-square	p -value
ModelA1	Year	−0.005	0.007	−0.018	0.008	0.630	0.427
ModelB1	Year	−0.001	0.009	−0.018	0.017	0.010	0.935
ModelC1	Year	−0.010	0.010	−0.030	0.009	1.100	0.295
ModelD1	Year	−0.007	0.008	−0.024	0.009	0.730	0.393
ModelE2	Year	−0.004	0.011	−0.025	0.016	0.160	0.690
	c1	−0.161	0.063	−0.283	−0.038	6.620	0.010
	s1	−0.078	0.062	−0.200	0.045	1.550	0.214
	ψ	0.179	0.063	0.056	0.302	8.121	0.004
	θ	3.593	0.154	3.291	3.895	545.316	<0.001