## Section 3: Statistical Modeling

### Instructor:

In many studies, multivariable statistical models are used to estimate an effect after controlling for a number of extraneous factors. For example, a statistical model might be used to estimate the effect of an intervention on 30-day mortality probabilities, adjusting for the severity of the patient s condition at the time of the intervention. Statistical models are also used for predicting outcomes, such as final diagnosis or in-hospital mortality. This section describes the uses, interpretation and limitations of statistical models.

### Learning Objectives

- To discuss simple linear regression.
- To discuss the use of regression models for prediction and inference.
- To discuss the use of multivariable techniques for statistical adjustment and improvements in inference.
- To fit nonlinear patterns in data through the use of piecewise polynomial regression models.

### Required Reading

- K&S Chapters 10-13, Sections 29.1-29.3, 29.8, 30.2, 38

**Recommended Reading**
- Spanos, Harrell, and Durack, JAMA 262: 2700; 1989.
- Harrell, Lee, and Pollock, J Nat Cancer Institute 80: 1198; 1988.