The data corrosion consists of thirteen specimens of 9010 Cu

The data corrosion consists of thirteen specimens of 90/10 Cu-Ni alloys with varying iron content in percent. The specimens were submerged in sea water for 60 days and the weight loss due to corrosion was recorded in units of milligrams per square decimeter per day.

(a) Calculate the mean and variance of weight loss for each of the distinct iron (Fe) values. (Variance cannot be calculated with less than two values.)

(b) Plot the log of the variance versus the log of the mean and comment on whether a transformation is required. If a tranformation is required, suggest the transformation.

(c) Fit the simple linear regression of loss on F e, and include the summary and anova outputs.

(d) Do a lack of fit test for this model. i. State the hypotheses. ii. Calculate the test statistic, showing calculation of the pure error and lack of fit sums of squares. iii. Give the degrees of freedom, and calculate the P value (i) using the tables and (ii) using R iv. State a conclusion in the context of the problem.

PLEASE SHOW ALL IN R CODE.

THANK YOU

Solution

(a).

The mean and variance of weight loss for each of the distinct iron (Fe) values

mean=0.8730          (using Excel)

Variance=0.4757

(c).