Table 2.

Analysis of variance (anova) for the fitted quadratic polynomial model of l‐DOPA production.

Source	Sum of squares	d.f.	Mean square	F‐value	P‐value P > F
Model	19.84159	14	1.417257	29.06809	< 0.0001*
X1 – pH	1.521544	1	1.521544	31.20704	< 0.0001*
X2 – tryptone	0.608851	1	0.608851	12.4876	0.0033*
X7 – l‐tyrosine	2.79271	1	2.79271	57.27879	< 0.0001*
X8 – CuSO4	1.112034	1	1.112034	22.80794	0.0003*
X1X3	0.457652	1	0.457652	9.386498	0.0084*
X1X7	0.937024	1	0.937024	19.21847	0.0006*
X1X8	0.349281	1	0.349281	7.163792	0.0181*
X3X7	0.134689	1	0.134689	2.762486	0.1187
X3X8	0.189225	1	0.189225	3.881026	0.0689
X7X8	0.693056	1	0.693056	14.21466	0.0021*
X12	2.448766	1	2.448766	50.22446	< 0.0001*
X32	0.952366	1	0.952366	19.53313	0.0006*
X72	7.215174	1	7.215174	147.984	< 0.0001*
X82	5.102503	1	5.102503	104.6529	< 0.0001*
Residual	0.68259	14	0.048756
Lack of fit	0.617689	10	0.061769	3.80695	0.1047
Pure error	0.064901	4	0.016225	29.06809	< 0.0001*
Corrected total	20.52418	28	1.417257	31.20704	< 0.0001*

^*Significant P‐values at P ≤ 0.05.