Researchers measured the specific activity of the enzyme sucrase extracted from portions...

Researchers measured the specific activity of the enzyme sucrase extracted from portions of the intestines of 24 patients who underwent an intestinal bypass. After the sections were extracted, they were homogenized and analyzed for enzyme activity [Carter (1981)]. Two different methods can be used to measure the activity of sucrase: the homogenate method and the pellet method. Data for the 24 patients are shown here for the two methods:

a. Examine the scatterplot of the data. Might a linear model adequately describe the relationship between the two methods?

b. Examine the residual plot: are there any potential problems uncovered by the plot?

c. In general, the pellet method is more time-consuming than the homogenate method, yet it provides a more accurate measure of sucrase activity. How might you estimate the pellet reading based on a particular homogenate reading?

d. How would you develop a confidence (prediction) interval about your point estimate?