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Table 3 ANOVA test performed on the second-order polynomial model used to discriminate between the significant linear (L) and quadratic (Q) effects of the investigated variables, as well as their interactions, for the investigated system and response (biohydrogen production)

From: Revealing the factors influencing a fermentative biohydrogen production process using industrial wastewater as fermentation substrate

  Sum of squares (SS) Degree of freedom Mean square F-value P-value
X1-L 270.935* 1* 270.935* 11.63704* 0.001725*
X1-Q 260.138* 1* 260.138* 11.17333* 0.002075*
X2-L 1314.436* 1* 1314.436* 56.45696* 0.000000*
X2-Q 185.342* 1* 185.342* 7.96069* 0.008033*
X3-L 61.992 1 61.992 2.66265 0.112237
X3-Q 0.236 1 0.236 0.01013 0.920420
X1X2 140.261* 1* 140.261* 6.02441* 0.019553*
X1X3 15.980 1 15.980 0.68634 0.413363
X2X3 0.291 1 0.291 0.01250 0.911647
Lack of fit 273.054 5 54.611 2.34561 0.062915
Pure error 768.309 33 23.282 - -
Total SS 3290.973 47 - - -
  1. *Values considered statistically significant.