Where α is number of moles of TEOS, β is the number of moles of NH 4 OH and γ is the number of fractionated additions of TEOS. The parameter estimates for the equation can be seen in Table . The model was found to agree well with the data with an r 2 of 0.74 and RMSE of 5.00 (Table ). Analysis of variance (ANOVA) demonstrated the model was highly significant with a p-value of < 0.0001. As such, the model explains the variance in the outcome, and H 0 is rejected. A plot of actual vs. predicted response for shell thickness, determined from the regression analysis, is presented in Fig. and demonstrates the success of the model.