This document discusses various formal research designs used in market research and methodology. It describes the basic principles of formal experimental design including replication, randomization, and local control. It then defines and provides examples of different types of formal designs like completely randomized design, randomized block design, Latin square design, and factorial designs. Factorial designs allow determining the main effects of two or more factors in a single experiment and permit other comparisons of interest. Complex factorial designs are used for experiments with more than two factors.