Google

Interaction effects in factorial experiments can be visually interpreted and analyzed using either bar graphs or line graphs. In these visualizations, spreading interactions are identifiable when there is a large difference in the dependent variable at one level but little to no difference at the other. Cross-over interactions are characterized by a distinct reversal in the pattern of bar heights or by line graphs where the plotted lines literally intersect and cross over one another.

Graphing Interactions

When interaction effects are depicted using bar graphs, specific visual patterns emerge. In a spreading interaction, the height difference between the comparison bars is prominent at one level of the independent variable on the horizontal axis, while there is little to no difference between the bars at the second level. Conversely, for a cross-over interaction, the relative pattern of the bar heights completely reverses between the two levels of the variable.

Bar Graphs of Interactions

When analyzing an interaction where one of the independent variables is quantitative, the data is typically plotted using a line graph. In these specific visualizations, a spreading interaction is demonstrated by lines that start together and diverge, indicating a growing effect at one level but not the other. A cross-over interaction is distinctly shown when the two plotted lines literally intersect and cross over each other, visually representing opposite effects across the conditions.

Learn Before

Related