12.12 - Summary

In 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.