The complex experimental and correlational designs available in behavioral and health related research, particularly in relation to multivariate analysis, are reviewed presented with examples. The roles of control groups, randomization, and matching are discussed in relation to complex designs using multiple groups and repeated measures. Types of randomization are discussed. The importance of validity, reliability, sensitivity, and specificity are covered as well as types of error. Multifactorial analysis and use of multivariate data analysis programs.