The article "Change in Creep Behavior of Plexiform Bone with Phosphate Ion Treatment" (R. Regimbal, C. DePaula, and N. Guzelsu, Bio-Medical Materials and Engineering, 2003:11-25) describes an experiment to study the effects of saline and phosphate ion solutions on mechanical properties of plexiform bone. The following table presents the yield stress measurements for six specimens treated with either saline (NaCl) or phosphate ion (Na2HPO4) solution, at a temperature of either 25◦C or 37◦C. (The article presents means and standard deviations only; the values in the table are consistent with these.)


a. Estimate all main effects and interactions.
b. Construct an ANOVA table. You may give ranges for the P-values.
c. Is the additive model plausible? Provide the value of the test statistic and the P-value.
d. Can the effect of solution (NaCl versus Na2HPO4) on yield stress be described by interpreting the main effects of solution? If so, interpret the main effects, including the appropriate test statistic and P-value. If not, explain why not.
e. Can the effect of temperature on yield stress be described by interpreting the main effects of temperature? If so, interpret the main effects, including the appropriate test statistic and P-value. If not, explain why not.