GoalTallyQuick answer: To make an ABA graph, enter one data point per session and start a new phase wherever the condition changed (for example, baseline to intervention). The graph maker draws a dashed phase-change line, breaks the data path between phases and labels each condition. Turn on a least-squares or split-middle trend line, an aim line and a mastery criterion if you need them, then download a PNG for a report or a PDF with a phase summary.
How to make an ABA graph in 5 steps
- Name the graph. Add the student's initials (not their name), the target behavior or skill, and the y-axis label, such as Percent correct or Rate per hour.
- Enter your data. One row per session, with an optional date. Press Enter to jump to the next session, or paste columns straight from Excel or Google Sheets.
- Mark phase changes. Add a phase for each condition (Baseline, Intervention, Maintenance) and set the session where it starts. The data path breaks at every phase-change line.
- Add lines. Turn on a trend line (least squares or split-middle), an aim line from baseline to the goal, and a mastery criterion such as 80% for 3 consecutive sessions.
- Download. Get a 2000 × 1240 px PNG for slides and reports, or a vector PDF with a summary table and an editable progress note.
What a standard ABA line graph includes
Behavior analysts follow shared visual conventions so that anyone can read a graph quickly and judge whether behavior changed when the condition changed. GoalTally applies them by default:
| Element | Convention | In GoalTally |
|---|---|---|
| Axes | Sessions or dates along the x-axis; the measure (percent, count, rate, duration) up the y-axis. | Session numbers or a true calendar axis, with any y-axis label. |
| Data points and path | One marker per session, joined by straight lines within a phase. | Filled circles, with open squares and triangles for a second and third series. |
| Phase-change lines | A vertical dashed line between the last session of one condition and the first session of the next. | Drawn halfway between the two sessions. |
| Broken data path | Points are never connected across a phase-change line. | Automatic. Missed sessions also break the line unless you choose to connect them. |
| Condition labels | A short name centered above each phase. | Taken from your phase names; long names wrap onto two lines. |
| Floating zero | Zero sits slightly above the x-axis so zero values stay visible. | On whenever the y-axis starts at 0. |
| No chart junk | No gridlines, 3-D effects or background shading. | Black-and-white style by default; a color style is optional. |
Trend lines: least squares or split-middle?
A trend line summarizes the direction and steepness of the data within one phase. GoalTally draws one per phase, on the first data series, once a phase has at least 3 data points, and the legend names the method used.
| Method | How it's calculated | When to use it |
|---|---|---|
| Least squares (ordinary least-squares regression) | The straight line with the smallest total squared vertical distance to all the points in the phase. | A good default for reports. It uses every data point, so one extreme value can pull it. |
| Split-middle (White's line of progress) | Split the phase in half by session, join the median session and median value of each half, then slide the line up or down, keeping its slope, until half the points fall on or above it and half on or below. | Resistant to outliers, and the method many behavior-analytic courses teach for visual analysis. |
With an odd number of points, the middle point is left out when the two halves are formed and counted again when the line is shifted. The summary table under the graph always reports the least-squares slope per session (or per week on a date axis), so you have a number to quote.
Aim lines and mastery criteria
An aim line, also called a goal line, joins the student's starting level to the goal by the target session or date, so you can see at a glance whether progress is fast enough. Click Start at the baseline median to begin the line at the median of the baseline phase, then enter the goal value and when it should be reached.
The mastery check reads your criterion, for example at or above 80% on 3 consecutive sessions or at or below 2 incidents for 5 sessions, and reports the first session where it was met. Sessions without data are skipped rather than counted as failures. The summary also lists each phase's mean, median, range, trend and PND (the percentage of non-overlapping data compared with the phase before).
Reading the graph: six things to compare
Visual analysis compares adjacent phases on six features:
- Level: how high or low the data sit (the phase mean or median).
- Trend: the direction and steepness of change within the phase.
- Variability: how much the points bounce around the trend.
- Immediacy: how quickly behavior changes after the phase change.
- Overlap: how many points in one phase fall within the range of the other.
- Consistency: whether similar phases (for example, both baselines in an ABAB design) look alike.
The summary table gives you numbers for level, trend and overlap. Variability and immediacy are easiest to judge by eye on the graph itself.
Data sheets for every measurement type
Collect the data, then graph it. GoalTally also makes printable data sheets, and you can score a session on a tablet and send it straight to the goal's graph.
Private by design
Everything happens in your browser. Graphs, sheets and saved goals are kept in this browser's storage on your device and never uploaded, so we can't see them. Use initials rather than names, and download an encrypted backup (under Backup, restore & export) before clearing browser data or switching devices. GoalTally is a free tool, not a records system, so follow your school's or clinic's data policies too.
Frequently asked questions
Is this ABA graph maker free?
Yes. Every feature is free with no account: unlimited graphs, PNG and PDF downloads, saved goals, data sheets, on-screen scoring and backups. A small “Made with GoalTally” credit appears under exported graphs.
How do I add a phase change line?
Click Add phase change, name the new condition and set the session where it starts. The dashed line is drawn halfway between the last session of the old phase and the first session of the new one, and the data path breaks there.
Can I graph two data paths, such as independent and prompted responses?
Yes. Choose 2 or 3 series. Each gets its own marker (filled circle, open square, filled triangle) and a legend entry. Trend lines, the aim line and the mastery check use the first series.
Can I paste data from Excel or Google Sheets?
Yes. Copy the cells and paste them into Paste from Excel or Google Sheets. It reads a header row (Session, Date, Phase, Value), the one-column-per-phase layout many Excel templates use, phase names on their own lines, or a plain list of numbers.
Does it work for IEP progress monitoring?
Yes. Switch the x-axis to calendar dates, add an aim line from baseline to the annual goal, and use the progress note as a starting point for your report. The IEP progress monitoring graph page has a worked example.
Where is my data stored?
Only in your browser on this device. Nothing is uploaded. Saved goals stay until you delete them or clear your browser data, so download an encrypted backup regularly.
Can I use the graphs for a BCBA course assignment or a report?
Yes, the PNG and PDF are yours to use. Check your course's or employer's graphing requirements, since some ask for a specific axis range, font or figure caption.
More free graphs and data sheets
Last updated · Written by the MiniTools team.