We think of DNA as the stuff that stores the genetic code. It turns out that DNA occurs mainly outside living cells, on the ocean floor. It is important in nourishing seafloor life. Scientists think that this DNA comes from organic matter that settles to the bottom from the top layers of the ocean. Phytopigments, which come mainly from algae, are a measure of the amount of organic matter that has settled to the bottom. The file "dna_oceanfloor.jmp" contains data on concentrations of DNA and phytopigments (both in grams per square metre) in 116 ocean locations around the world. Does the data give good reason to think that phytopigment concentration helps to explain DNA concentration?
(a) Using an appropriate graphical display, describe the relationship between DNA and phytopigments.
(b) Fit a regression line to the data. Write down the equation of the model and interpret all parameters in the model.
(c) Test the hypothesis of no linear relationship between DNA and phytopigments. Show all steps.
(d) Using JMP, obtain 95% confidence intervals for the intercept and slope. Interpret.
(e) Critically assess the model. Does your assessment suggest any problems with the fitted regression model?
(f) Predict the DNA concentrations when phytopigment concentration equals to 0.07 gr/m2 and 0.09 gr/m2 respectively.