ABSTRACT
In the following chapters I shall be referring to independent variables as factors as that is the term used in the analysis of variance, so age, hair colour and type of school attended are all examples of factors. The conditions are the categories of the independent variable we choose to study. These are also referred to by other terms such as groups, levels or treatments, but I shall use conditions throughout. If we were investigating the independent variable of age we might select the conditions: 20 year olds, 40 year olds and 60 year olds. These age groups are the three conditions of the factor under study. We could, of course, choose different conditions for the variable age if we wish.
