Mosfeldt et al. (2012) collected data on 792 patients age 60 or over who were admitted to a hospital in Denmark with a hip fracture between 2008 and 2010. They reported that an elevated creatinine level upon hospital admission for a hip fracture (>90 mmol/L for women and >105 mmol/L for men) is associated with an almost threefold increase in mortality risk.

What is the independent variable? What level of measurement is it? What is the dependent variable? What level of measurement is it? What type of sample is this? Is it a probability or nonprobability sample? These researchers chose to use a regression model. Should they perform a linear regression, multiple regression, or logistic regression? Why?