Low potato yields in Kenya: do conventional input innovations account for the yields disparity?

Table 6 Nonlinear and linear regression on yields

	Linear regression		Nonlinear regression
Yield	Coefficient	P value	Coefficient	P Value
Fertilizer use per acre	0.01168	0.001**	0.0362579	0.00***
Fertilizer use per acre squared			-0.0000605	0.001***
Clean seeds	3.11066	0.041*	2.450674	0.109
Use fungicides	1.84136	0.138	2.322216	0.037**
Constant	9.06671	0	7.172435	***
R ²	4.78		8.54
	Controlling for social-economic characteristics
	Linear regression		Nonlinear regression
Yield	Coefficient	P Value	Coefficient	P Value
Fertilizer use per acre squared			-0.0000483	0.009**
Fertuse per acre	0.0070554	0.056*	0.0273886	0.001***
Use clean seeds	2.190173	0.165	1.805383	0.25
Use fungicides	2.667031	0.018**	2.352725	0.037*
Has irrigation equipment	0.5149959	0.56	0.6793034	0.44
Size of land owned	0.0548732	0.427	0.0420069	0.541
Education - Secondary Sch. & above	0.3303141	0.624	0.387795	0.563
Gender (Female)	-1.812674	0.027**	-1.794205	0.027**
Not employed	-0.3628529	0.751	-0.1604294	0.888
Retired	-1.093352	0.415	-1.040537	0.434
Age ( 40 -49 years)	-1.060726	0.225	-1.005677	0.246
Age (50-59 years)	0.1877138	0.833	0.4085131	0.646
Age (Above 60 years)	-1.264216	0.204	-0.9387634	0.345
Region - Central	-2.018409	0.033**	-1.752407	0.064*
Region - Rift Valley	-2.733439	0.006**	-2.257026	0.025**
Visited by Agr. Officer	0.4646729	0.507	0.2337566	0.738
Own Radio or TV	-1.090301	0.365	-1.092433	0.36
Member of farmer group	0.1880047	0.794	0.1577523	0.826
Number of cows	0.0860794	0.601	0.0973959	0.551
Constant	11.76595	0.000***	10.34928	0.000***
R squared	12.3		13.82

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