Graphical representations of factorial experiments vary based on the nature of the variables involved. For instance, in a $2 imes 2$ design, researchers might use a bar graph with a categorical variable like 'time of day' on the $x$-axis and 'cell phone use' indicated by different colored bars. Conversely, for a $4 imes 2$ design that includes a quantitative variable, a line graph is typically used; here, the quantitative variable, such as 'psychotherapy length', is placed on the $x$-axis, while the categorical variable, like 'psychotherapy type', is represented by distinct line formats.