ABA glossary
Trend
Definition
The overall direction of a data path over time (increasing, decreasing, or flat) and how steep that change is.
In plain words
Trend tells you where the data are heading. You look across several data points in the same phase, not at the change from one session to the next. An increasing trend in correct responses means learning is happening; a decreasing trend in problem behavior means the plan may be working. A flat (zero) trend means no change. Trend is read together with level (where the data sit) and variability (how much they bounce), because a lot of bounce can hide or fake a trend.
Example from a session
The RBT updates Ella's graph after each session: percentage of steps completed independently in hand washing is 20, 30, 45, 40, 55, 65 across six sessions. Even though one session dipped, the overall direction is up: an increasing trend. The RBT reports what the graph shows and leaves decisions about mastery or changes to the BCBA.
For BCBA candidates and supervisors
Analysts describe trend by direction and degree, and sometimes draw a trend line, such as the split-middle line of progress or a least-squares line, to judge it more consistently. Trend in baseline drives design decisions: an improving baseline trend makes it hard to show that the intervention caused further improvement, so analysts wait for stability or choose a design that can handle it. A trend that continues from baseline into intervention at the same slope is not evidence of an effect.
Often confused with level, variability
Trend is direction and slope over time. Level is where the data sit on the y-axis, often summarized by the mean or median. Variability is how much the points bounce around. "Tantrums are high" describes level; "tantrums are going down" describes trend; "tantrums jump from 2 to 15 and back" describes variability.
Exam tip
Look at the whole phase, not the last two points. If the question asks about direction or whether behavior is "getting better or worse over time," it is about trend. If it asks how high the data are, it is level.
Can you spot trend in a scenario?
Practice RBT A.7 with exam-style questions and instant feedback.