# 12.12 - Summary

12.12 - SummaryIn this lesson, among other things, we learned:

- Differentiate between means and adjusted means.
- State how ANCOVA can reduce difficulties resulting from imbalance in prognostic factors.
- Recognize situations in which using a prognostic factor as a covariate is recommended. Recognize the difficulty presented with time-dependent covariates.
- Recognize interaction effects and differentiate between qualitative and quantitative interactions.
- Select the appropriate analysis of the data among ANCOVA, logistic regression and proportional hazards.
- Modify SAS programs to perform ANCOVA and logistic regression. Interpret the relevant portions of SAS output for these analyses.
- Identify 4 approaches to model building.
- Recognize the effects of incomplete data on model-building.
- Propose two methods of validating a model from a nonrandomized study.