Standard Celeration Chart Symbols and Conventions

Pick up a Standard Celeration Chart drawn by another clinician, school, or Precision Teacher, and you should be able to read it without asking a single question. That’s the promise of the SCC’s charting conventions: everyone uses the same symbols, drawn the same way, on the same chart.

This guide is a plain-language key to the most common Standard Celeration Chart symbols: what each one means, how it’s drawn, and why it’s there. We’ll also note how SimpleSCC handles each one. If you’re brand new to the chart itself, start with What is the Standard Celeration Chart? and come back.

Why SCC Symbols Are Standardized

Ogden Lindsley designed the SCC so charts could be shared and compared. The scales are fixed, so a ×2 celeration looks the same on every chart. The symbols are fixed too, so a dot means the same thing no matter who drew it. That consistency is what lets you flip through a stack of charts in a team meeting and spot, in seconds, which learners need help.

Details vary a little between charting guides, and between paper and software. The core symbols below are the ones you’ll see almost everywhere.

Dots for Accelerations, X’s for Decelerations

The two most important symbols on the chart tell you which way a behavior is supposed to go:

• Dot (•): an acceleration target. Use a dot for a behavior you want to increase, like correct answers, requests, or words read correctly.
• X (×): a deceleration target. Use an X for a behavior you want to decrease, like errors or a problem behavior.

In academic programs, the classic pairing is corrects as dots and errors (often called learning opportunities) as X’s on the same chart. Read together, the two form a learning picture. The one everyone hopes to see has dots climbing while X’s fall, so the two trends open apart like a mouth; charters often call this picture “jaws.”

Charting both on one chart catches problems a single line would hide. If corrects are climbing but errors are climbing just as fast, the learner is getting faster, not more accurate.

In SimpleSCC: each target on a chart is set to Increase or Decrease and given its own marker. Dots and X’s are available, along with open circles and closed or open triangles for charts that track more than two behaviors.

The Record Floor Dash

The record floor is a short horizontal dash drawn on the day’s line at 1 ÷ the counting time in minutes. It marks the lowest non-zero rate you could have recorded: one count in the time you observed.

• 1-minute timing: dash at 1 per minute.
• 10-second timing: dash at 6 per minute.
• 20-minute observation: dash at 0.05 per minute.

Draw a floor every day you chart, even if it’s the same as yesterday’s. Floors show how much of the chart your measurement can actually see, and a floor sitting just under the data warns you that the timing may be too short to show real change. The paper chart lists common counting times down its right-hand edge so you can place the dash without doing the arithmetic. You may also see the record floor called the timing floor.

In SimpleSCC: you enter the time spent alongside each count, and the floor dash is drawn automatically at the right height.

The Record Ceiling

Some procedures put a cap on the count. If a worksheet has 20 problems and the timing lasts one minute, the highest possible rate is 20 per minute. A record ceiling is a dash at that maximum, the mirror image of the floor. A learner sitting at the ceiling may be capable of much more; the measurement just can’t show it.

Ceilings come up often in ABA because discrete trial teaching usually runs a fixed number of trials, which caps the count. If your data keep bumping against the same value, a ceiling is the likely reason.

In SimpleSCC: ceilings aren’t drawn yet, so keep any cap from your procedure in mind when reading data near the top.

Charting a Zero

Zero is real data. It means the behavior had a chance to happen and didn’t. But a log scale has no place for zero (you can halve a number forever without reaching it), so the convention is to chart a zero just below that day’s record floor. That keeps it visually separate from any count you actually recorded.

In SimpleSCC: zero counts sit on a separate zero line at the very bottom of the chart, below the log scale, so a zero can never be mistaken for a very low rate.

Ignored Days and No-Chance Days

Because the daily chart’s horizontal axis is calendar days, every day appears on the chart, and charters distinguish two kinds of days without data:

• Ignored day: the behavior could have happened, but nobody recorded it.
• No-chance day: the behavior couldn’t have happened. School was closed, the learner was absent, or the program didn’t run.

On paper, the difference shows up in how data points are connected. Lines joining a phase’s data points run across ignored days but stop at no-chance days. That way, anyone reading the chart can tell “we missed it” from “it wasn’t possible.”

In SimpleSCC: data points aren’t joined by lines, so a day without data simply stays blank, whichever kind of day it was.

Phase Change Lines

A phase change line is a vertical line drawn between the last day of one condition and the first day of the next, any time something about the teaching or the environment changes. The conventions:

• Label it with a short description of what changed, such as “Added modeling” or “New reinforcer.”
• Don’t connect data points across a phase change line, and don’t draw a celeration line across one. Each phase gets its own line and its own celeration value.

That last rule is what makes before-and-after comparisons possible. With a separate celeration line on each side, you can read the frequency jump (the immediate step up or down at the line) and the celeration turn (the change in steepness) that came with the change.

In SimpleSCC: add a phase line by choosing its date and typing a short label; the label runs down the line on the chart.

Celeration Lines and Bounce Lines

A celeration line is a straight line through a phase’s data that summarizes its trend. Its value is written as a multiplier per week, such as ×1.4 (growing 40% each week) or ÷2.0 (halving each week), usually right next to the line.

Bounce lines run parallel to the celeration line, one through the highest point and one through the lowest, to show how much the data vary around the trend. Bounce is written as a multiplier too. A bounce of ×2 means the best days are about twice as high as the worst, relative to the trend.

In SimpleSCC: the celeration line, a two-week projection of it, and the bounce envelope can each be switched on, and the celeration and bounce values are calculated for you.

Aim Stars

The aim star marks the goal: the frequency you want the learner to reach and the date you want them to get there by. It’s drawn where the aim frequency and the aim date meet. The exact shape varies a little between charting guides, but the meaning doesn’t.

With the aim on the chart, you can lay a ruler along the current celeration line and see immediately whether it passes through the aim star, or whether something needs to change now rather than in six weeks.

In SimpleSCC: set an aim for the chart in count per minute, and it’s marked at that level along the chart’s left edge.

Chart Labels

The paper chart has blanks around its edges for the details that make a chart readable later: what was counted (the pinpoint), who was charted, who did the counting and timing, and the setting. A good pinpoint is specific enough that two people watching the same session would count the same thing: “says letter sounds” or “writes digits,” not “reading” or “math.” For a step-by-step method, see How to write a Pinpoint+.

One modern addition: if your charts live in software that isn’t built for protected health information, label learners with initials or codes rather than names. SimpleSCC works that way, and its terms require de-identified data.

Quick Reference: SCC Symbols at a Glance

• Dot (•): acceleration target, a behavior to increase.
• X (×): deceleration target, a behavior to decrease.
• Dash at 1 ÷ counting time: record floor.
• Dash at the highest possible rate: record ceiling.
• Symbol just below the floor: a count of zero.
• Data line runs across a blank day: ignored day.
• Data line stops at a blank day: no-chance day.
• Vertical line with a label: phase change.
• Straight line through a phase, marked × or ÷: celeration line.
• Parallel lines above and below the celeration line: bounce envelope.
• Aim star: the frequency aim and the date to reach it.

Chart It Without the Ruler

Conventions are what make the SCC a shared language, but drawing them by hand on log paper is slow. SimpleSCC handles the plotting, floors, celeration, and bounce for you, so your charts stay standard and your time goes to decisions. You can try SimpleSCC for free, or read SCC vs. Equal-Interval Graphs: What Are We Missing? to see why the scale is worth learning.