A scatter plot for identifying stimulus control of problem behavior.

The authors watched three clients and marked every instance of problem behavior.

They wrote the time and the activity on the same sheet.

Instead of averaging the data, they made a scatter plot: time on the bottom, activity on the side, and a dot for every problem moment.

The dots clumped in clear stripes or blocks.

Those clumps showed that only certain times or certain activities set off the behavior.

Averaged line graphs had hidden these hot spots.

Webb et al. (1999) later used the same trick in preschool. They plotted problem behavior by presumed function, not by clock time. Their graphs gave faster FBA hypotheses.

Mueller et al. (2000) kept the separate-trace idea but split the data by response shape instead of by activity. Both papers warn: lumping hides the real story.

Haddock et al. (2020) pooled dozens of studies and still recommend scatter plots as a first step before any competing-stimulus test.

You can build the plot in a single day. Just keep a clipboard, mark the time and the task when the behavior hits, then drop dots on a blank grid. The finished picture tells you when to look deeper and when to skip. Use it Monday to pick the right moment for your functional analysis or to see if your treatment really flattened the clump.