A financial analyst for a bank wants to analyze the relationship between customer’s credit scores and

home-ownership. She suspects that renters have on average lower credit scores than home owners, and that credit scores improve over the time that customers live in their current residence. A linear regression model with these two variables confirms her suspicions. However, she now wonders whether the time lived at current residence equally affects home owners and renters. To answer this question, which variable (or variables) should the analyst include in her regression model?

a.dummy variables for the renters who have lived in their current residence the longest