The basic steps for evaluating an intervention in single-subject research are as follows: First, you measure the behavior repeatedly under the baseline condition. Then, you implement the intervention or the treatment for several days, continuing to measure the behavior. As you are collecting the data, you graph it so that you can see whether there is a change in the behavior under the intervention. Visual analysis means that you are evaluating your data visually, based on what you see.
Measure the behavior repeatedly in the baseline phase.
Implement the intervention and measure the behavior repeatedly in the intervention phase.
GRAPH the data and use VISUAL ANALYSIS to decide if the intervention caused a change in the behavior.