Functional analysis of problem behavior: A systematic approach for identifying idiosyncratic variables.

Researchers tried a four-step FA on 20 clients with mixed diagnoses. They started with short 5-minute conditions. If results were unclear, they added longer sessions and extra test conditions.

The goal was to turn muddy, inconclusive FAs into clear, repeatable patterns you can trust for treatment.

The phased plan worked for 17 out of 20 cases. Each client ended with one clean function you could see across sessions.

Three clients still showed mixed or no control, but the team knew when to stop and try other tools.

Henry et al. (2021) used the same brief-to-extended idea and hit 100% clarity. They added quick confirmation and annulment probes—tiny checks that either strengthen or wipe out the first finding. Those extra probes explain the jump from 85% to 100%.

Guest et al. (2013) took a different path to the same goal. When staff FAs were unclear, they let trained caregivers run the next round. Caregiver FAs cleared up function and later treatments cut problem behavior by 96%. Both papers show you can rescue an inconclusive FA; one does it with longer phases, the other with a new implementer.

Saini et al. (2024) also starts small. Their 10-minute screening FA for food refusal matched the full FA every time. It mirrors the brief-first spirit but stays short instead of expanding.

Start your next FA with a 5-minute test. If the data look messy, add time and new conditions instead of quitting. This staged approach saves hours and gives you a clear reinforcer to build treatment around.