Process Optimization for Biodiesel Production from Corn Oil and Its Oxidative Stability

Table 3

2² factorial design: statistical analysis.

Response:	𝑌(%)
Number of experiments:	4
Degree of freedom:	3
Results of statistical analysis
𝑌 (average)	97.16
Main effects and interactions
𝑋𝑇=1.66,  𝑋𝐶=3.41,   𝑋𝑇𝐶=−0.43
Statistical Significance of 𝑡-test
Confidence level: 95%,	Standard deviation, 𝑆=0.24
Student’s 𝑡 value, 𝑡=3.182,	Confidence interval: ±0.38
Significant effects and Interactions: 𝑋𝑇(+),𝑋𝐶(+),𝑋𝑇𝐶(−)
Statistical significance of curvature
𝑌𝐶=98.2,𝑌=97.16	Curvature: 𝑌𝐶−𝑌−=1.04
𝑆=0.11,𝑡=3.182	Confidence curvature interval: ±0.54
	Curvature: significant
Response equation:
𝑌=97.16+1.7𝑋𝐶+0.83𝑋𝑇−0.21𝑋𝑇𝐶	𝑟=0.98