highly significantp = 0.002
In the coded linear model, the intercept (constant term) of 5.8625 ( p < 0.001) described the mean pH at the design center, whereas the coefficient for PAW treatment time (Term B) was strongly negative (− 1.0750) and statistically highly significant ( p = 0.002), corresponding to a large, standardized effect size indicating that lengthening the activation from 0 to 20 min reduced pH by more than one unit over the studied space.