Absolute values of the effects of main factors and the interaction of factors are also provided in the Pareto chart (Fig. 9). It could be observed that they are in accordance with the previous results. In Fig. 9, for t-value equal to 2.12, a reference was dressed which corresponds to the 95% confidence level. The values that exceed this reference line, i.e., those corresponding to the 95% confidence in- terval, are significant values (Mathialagan and Viraraghavan, 2005).
According to Fig. 9, the main significant factors are: Temperature and duration of dyeing process followed by the interaction between dyeing duration and dyeing temperature and the pH of the dye bath.