ABA Exam CoachFunctional behavior assessment vs functional analysis
These two terms sound almost the same, and plenty of people use them interchangeably. On the exam they aren't interchangeable.
- A functional behavior assessment (FBA) is the whole process of identifying what maintains a behavior. It's the umbrella.
- A functional analysis (FA) is one method inside that process: the one where you deliberately change conditions and watch what happens to the behavior.
Every FA is part of an FBA. Not every FBA includes an FA. The BACB's 6th edition outline splits this into two tasks: designing and evaluating descriptive assessments (F.5) and designing and evaluating functional analyses (F.6).
The three families of FBA methods
| Method | What you do | What it can show |
|---|---|---|
| Indirect | Interview caregivers or use rating scales and questionnaires | People's reports. A starting hypothesis |
| Descriptive | Observe the behavior directly where it normally happens, recording what comes before and after (ABC recording, scatterplots) | Correlations between events and behavior |
| Experimental (FA) | Arrange test and control conditions and program consequences for the behavior | A functional relation: evidence of cause |
The key line is between the bottom row and the other two. Only an FA manipulates variables. Hanley, Iwata and McCord (2003) used exactly that as part of their definition when reviewing the FA literature: direct observation of the behavior under at least two conditions that manipulate an environmental variable, to show a relation between that variable and the behavior.
What a functional analysis looks like
Iwata and colleagues' study (first published in 1982, reprinted in JABA in 1994) exposed participants to brief, repeated sessions that differed in play materials, task demands and social attention. In six of nine participants, self-injury was consistently higher in one particular condition. That pattern pointed to what maintained the behavior.
Modern FAs usually compare conditions like these:
- Attention: the adult is busy and gives brief attention after the behavior. Tests social positive reinforcement.
- Demand (escape): tasks are presented and removed briefly after the behavior. Tests social negative reinforcement.
- Tangible: a preferred item is taken away and returned after the behavior. Tests access to items.
- Alone or ignore: little stimulation and no social consequence. Tests automatic reinforcement.
- Play (control): free attention, preferred items and no demands. Behavior should be low here.
If the behavior is reliably higher in one test condition than in the control, that condition suggests the function.
Worked examples and non-examples
- FA: a clinician runs alternating 10-minute attention, demand, alone and play sessions, scoring head hitting in each. This manipulates consequences, so it's an FA.
- Not an FA (descriptive): a teacher records what happened before and after every tantrum for two weeks. Nothing was manipulated. The data show correlations only.
- Not an FA (indirect): the BCBA gives the parent a rating scale about when the behavior happens. That's a report, not observation.
- Still descriptive: the caregiver is asked to present demands at set times but responds to the behavior however they normally would. Antecedents are arranged, but consequences aren't programmed, so it's usually classed as a structured descriptive assessment.
Why use one over another?
Descriptive and indirect methods are quicker and don't evoke the behavior on purpose, so they're useful early on and for choosing which FA conditions to include. Their weakness is that correlation can mislead. Attention may follow a behavior often simply because adults attend to almost everything, or a real reinforcer may be delivered too rarely to stand out.
An FA gives stronger evidence, but it deliberately sets up conditions that can evoke problem behavior. That calls for consent, a risk assessment, safeguards such as stopping criteria, and the training to run it safely. Scenario items often test this judgement: which method fits this client, this behavior and this setting?
Common traps
- Calling an ABC chart a functional analysis. If nothing was manipulated, it's descriptive.
- Saying an FBA "proves" the function. Only the experimental part can show a functional relation.
- Forgetting the control condition. Without a comparison condition, high rates in one condition are hard to interpret.
- Reading "functional assessment" in an option as "functional analysis". Read every option carefully. The words differ by one syllable.
- Assuming high rates in the alone condition mean "no function". Persistently high rates there suggest automatic reinforcement.
Practise it
For each assessment in a scenario, ask one question: did anyone manipulate the antecedents and consequences? If yes, it's an FA. If no, decide whether someone observed directly (descriptive) or reported (indirect).
The lessons on F.5: descriptive assessments and F.6: designing and reading functional analyses cover both in depth. Behavior Assessment is about 13% of the exam, so the free diagnostic is a quick way to see where you stand.
FAQ
Is a functional analysis the same as a functional behavior assessment? No. An FBA is the whole process of identifying function. An FA is the experimental method within it that manipulates variables.
What are the main types of functional behavior assessment? Indirect assessment (interviews and rating scales), descriptive assessment (direct observation without manipulation) and functional analysis (experimental manipulation).
Why is an FA considered stronger evidence? Because it compares conditions you control, it can show a functional relation. Indirect and descriptive methods can show only what people report or what tends to occur together.
Is ABC data collection a functional analysis? No. ABC recording is a descriptive assessment. It records natural events without manipulating them.
Sources
- BACB, BCBA Test Content Outline (6th ed.): https://www.bacb.com/wp-content/bcba-outline-6thEd (tasks F.5 and F.6)
- Hanley, G. P., Iwata, B. A., & McCord, B. E. (2003). Functional analysis of problem behavior: A review. Journal of Applied Behavior Analysis, 36(2), 147–185: https://pmc.ncbi.nlm.nih.gov/articles/PMC1284431/ (defining features of a functional analysis)
- Iwata, B. A., Dorsey, M. F., Slifer, K. J., Bauman, K. E., & Richman, G. S. (1994). Toward a functional analysis of self-injury. Journal of Applied Behavior Analysis, 27(2), 197–209 (reprinted from 1982): https://pmc.ncbi.nlm.nih.gov/articles/PMC1297798/ (analogue conditions varying materials, demands and attention)