Scenario: In Chapter 2, our first illustration of experimental data involved a study of the compressive strength of concrete. In this scenario, we look at a set of observations all taken at 28 days (4 weeks) after the concrete was initially formulated. The response variable is the Compressive Strength column, and we’ll examine the relationship between that variable and two candidate factor variables.

a. Use Cement as the factor and run a regression. Report on your findings in detail. Explain what this slope tells you about the impact of adding more cement to a concrete mixture.

b. Use Water as the factor and run a regression. Report on your findings in detail. Explain what this slope tells you about the impact of adding more water to a concrete mixture.