Table 3.

Model summary and parameter estimates

Country	Summary	Parameter Estimates
	R Square	Constant	β1	β2	β3
Bangladesh
Linear	0.767a	−33,018.645	1122.635
Quadratic	0.987a	13,105.539	− 1222.663	20.045
Cubic	0.999a	− 313.915	124.858	−8.625	0.163
Exponential	0.915a	9.628	0.098
Egypt
Linear	0.699a	− 8039.316	256.061
Quadratic	0.956a	4274.644	− 349.544	5.005
Cubic	0.995a	− 1566.637	218.015	−6.673	0.064
Exponential	0.893a	2.352	0.094
Cameroun
Linear	0.860a	− 2845.963	112.376
Quadratic	0.992a	591.439	−59.494	1.444
Cubic	0.993a	146.269	−15.528	.525	0.005
Exponential	0.820a	15.465	0.069
Ghana
Linear	0.894a	− 3633.083	156.014
Quadratic	0.995a	268.922	−49.354	1.817
Cubic	0.995a	183.709	− 40.501	1.622	0.001
Exponential	0.853a	29.047	0.068
Indonesia
Linear	0.887a	−10,357.170	422.333
Quadratic	0.997a	1439.768	− 157.844	4.795
Cubic	0.999a	− 550.761	35.562	.815	0.022
Exponential	0.782a	56.394	0.069
Mexico
Linear	0.823a	−50,669.386	1832.606
Quadratic	0.995a	14,390.013	− 1447.700	27.799
Cubic	1.000a	1958.116	− 209.705	1.682	0.148
Exponential	0.868a	97.206	0.079
Nigeria
Linear	0.785a	−4937.222	164.210
Quadratic	0.991a	1748.194	−164.581	2.717
Cubic	0.999a	151.233	−9.415	−.475	0.018
Exponential	0.911a	2.245	0.090
South Africa
Linear	0.667a	−29,085.662	929.637
Quadratic	0.941a	17,807.574	− 1395.647	19.377
Cubic	0.995a	− 7413.468	1074.917	−31.878	0.285
Exponential	0.865a	50.331	0.075

^aSignificant at 0.1%