This chapter defines the terms used throughout the book to analyse prevalent patterns in literature, thought and visual art in Ancient Greece (eighth to fourth centuries bce) and corelate them with the contemporary economic and political situation. Aggregation is defined as a paratactic sequence or assemblage of otherwise unrelated items. Antithesis is defined as the symmetrical representation of opposites. Antithesis is subdivided into antagonistic or peaceful, balanced or unbalanced, focused or unfocused. These are the central terms for this book. A further category, of less importance for this purpose, is asymmetrical opposition, which is subdivided into antagonistic and balanced or antagonistic and unbalanced or non-antagonistic.

Biological data commonly involve multiple predictors. This chapter starts expanding our models to include multiple categorical predictors (factors) when they are in factorial designs. These designs allow us to introduce synergistic effects – interactions. Two- and three-factor designs are used to illustrate the estimation and interpretation of interactions. Our approach is first to consider the most complex interactions and use them to decide whether it is helpful to continue examining simple interactions. Main effects – single predictors acting independently of each other – are the last to be considered. We also deal with problems caused by missing observations (unbalanced designs) and missing cells (fractional and incomplete factorials) and discuss how to estimate and interpret them.