What type of line is used to represent phase changes on charts?

The use of a solid vertical line to represent phase changes on charts is important because it clearly indicates a significant shift in the conditions or circumstances of the data being observed. Solid vertical lines provide a strong visual cue to the viewer that a change in the phase has occurred, such as the start or end of an intervention in a behavior analytic context.

In graphical representations, phase changes could denote a change from baseline to treatment, or from one treatment condition to another, making it essential to easily distinguish these points to interpret the data accurately. A solid line offers clarity and definite separation between phases, facilitating easier analysis of trends and effects between different conditions over time. The use of a solid vertical line is standard practice in visual analysis to enhance the overall readability and effectiveness of the data presentation.