A 23 factorial design has been run in duplicate for the purpose of studying in a research laboratory the effects of three variables (temperature, concentration, and time) on the amount of a certain metal recovered from an ore sample of a given weight. Analyze these data and state the conclusions you reach.
(a) Do you think that these data contain a discrepant value?
(b) Perform an analysis using all the data and plot residuals.
(c) Perform an approximate analysis omitting the discrepant value.
(d) Report your findings.