The antimicrobial activity of thyme oil against 7 common food-related bacteria and fungus tested is presented in Table 2. The null hypothesis that the inhibition zone is equal to the disc diameter (6 mm) was rejected for each microorganism at every amount of essential oil with a high significance level (p = 0.00). The main finding of the ANOVA analysis is a strong interaction effect between the type of microorganism and the amount of essential oil (p = 0.00). The highly significant interaction effect adds difficulty in drawing general conclusions on the main effects, even if the two factors are also highly significant (p = 0.00). For example, K. pneumoniae has the highest inhibition zone overall but for the amount of 20 [μL], where E. coli and S. typhimurium have higher values. In order to compare more thoroughly the effect of T. vulgaris on each microorganism (Fig. 1), the results of multiple comparisons, at each oil amount, has to be considered. Tukey’s HSD test reveals that the only microorganisms with non-significant differences in the antimicrobial effect are S. typhimurium and E. coli at all oil amounts, and S. typhimurium, E. coli and C. albicans at 10 [μL]. The observed p-value for the pairwise differences in the above-mentioned cases does not pass acceptable significance levels, being larger than 0.4. All the other pairwise differences are highly significant (p = 0.00).