The analysis of variance (ANOVA) shown in Table 2 indicates that the observed model for bio-oil yield gives good prediction at 95% confident level. For the bio-oil yield model, Fvalue is higher than F0.05 rejecting the null hypothesis. The student’s t-distribution and p-values of the model factors are shown in Table 3. The significance of each model coefficient can be analyzed by comparing smaller p-value of ⩽ 0.05 or greater t-value. The largest effects on bio-oil yield is from linear and quadratic terms of N2 flow rate with highest t-values (−5.60711, −5.0994) and lowest p-values (0.000225, 0.000464) at 99.98% and 99.95% significance levels, respectively. The interaction term CAC loading and microwave power (x1x2) can also be regarded as significant factor on bio-oil yield at 98.32% significant level.