Graphing IEP data: aimlines and trend lines

A progress monitoring graph has one job: show at a glance whether the student is on the path to the goal. The aimline is that path. The trend line is the path the student is actually on. When you can see both, decisions get easier and progress reports get shorter.

This guide sets up a graph step by step with one fictional student, then shows the mistakes that make graphs misleading. The IEP progress monitoring pillar explains where graphing fits in the full cycle.

Aimline and trend line: the difference

The aimline (also called the goal line) runs from the baseline to the goal on the date the goal is due. It is drawn once, at the start, and only changes if the IEP team changes the goal.

The trend line summarizes the student's actual scores. It is drawn from the data after several points and redrawn as data comes in. Comparing the slope of the trend line with the slope of the aimline is one of the standard ways to decide whether instruction is working.^[1]

Step by step

Step 1: Set up the axes

Put time on the horizontal axis, in weeks or dates, covering the whole IEP year. Put the goal's unit on the vertical axis: words correct per minute, digits correct, minutes, steps or percent. Start the vertical axis at 0 and run it a little past the goal so the line has room. Example: a goal of 38 digits correct gets an axis from 0 to 45.

Step 2: Plot the baseline

Plot the 3 or more baseline probes at the start of the graph and mark their median. The median is the starting point of the aimline. Example: baseline probes of 12, 15 and 14 digits correct give a median of 14. The guide on collecting baseline data covers how to get those points.

Step 3: Draw the aimline

Mark the goal value at the date the goal is due. Draw a straight line from the baseline median to that mark. To get the weekly growth the aimline expects, subtract the baseline from the goal and divide by the number of weeks. Example: (38 minus 14) divided by 32 weeks is 0.75 digits per week.

Step 4: Plot each probe

Add each score on the week it was given. Connect points with a line only within the same phase of instruction. Leave a gap for missed weeks instead of guessing a score.

Step 5: Mark changes with a vertical line

When instruction changes, draw a vertical line between the last point before and the first point after the change. Label it in a few words: "Added fact practice, 5 min daily." Do not connect points across that line. This turns the graph into a record of what was tried and what happened.

Step 6: Draw the trend line

After 6 to 8 points, draw a trend line. By hand, a common method splits the points into three equal groups. Find the median score and the middle week of the first group and of the last group, mark those two spots and connect them. In a spreadsheet, the SLOPE function on the scores and week numbers gives the weekly growth directly.

Step 7: Compare the two lines

If the trend line is about as steep as the aimline, continue. If it is flatter, change instruction. If it is steeper, consider raising the goal. The four-point rule and trend analysis guide sets out these decision rules in detail.

Time each step takes

Setup is about 8 minutes per goal. After that, the weekly cost is under a minute per goal.

Worked example: Ruby's math facts graph

Ruby is a fictional fourth grader. The numbers show the method only.

Goal: "Given a 2-minute probe of mixed addition and subtraction facts to 20, Ruby will write 38 digits correct by the annual review, 32 instructional weeks away." Each probe is scored as digits correct in 2 minutes, following rate per minute scoring, and recorded on the frequency data sheet.

Baseline: 12, 15 and 14 digits correct. Median 14.

Aimline: from 14 at week 0 to 38 at week 32, or 0.75 digits per week. The aimline value at week 9 is about 21.

First 9 weeks of probes:

Trend line by hand: The first group (weeks 1 to 3) has a median score of 15 at week 2. The last group (weeks 7 to 9) has a median score of 20 at week 8. The trend line runs from 15 at week 2 to 20 at week 8, a slope of 5 divided by 6, or about 0.83 digits per week.

Comparison: Ruby's trend (0.83 per week) is a little steeper than the aimline (0.75 per week). Her points sit on both sides of the aimline. Decision: continue instruction and check again at week 13.

In the progress report: "Ruby writes 20 digits correct in 2 minutes, up from 14. She is growing about 0.8 digits a week, slightly faster than the 0.75 she needs to reach 38 by the annual review." The progress report examples show more entries written straight from a graph.

Common mistakes

• Weak: Starting the aimline at the first probe after the baseline. Better: Start it at the baseline median, so one high or low day does not tilt the whole line.
• Weak: A vertical axis that starts at 12 to make growth look steep. Better: Start at 0, so the graph shows real size of change.
• Weak: Connecting points across a change in instruction. Better: A labeled vertical line with a gap, so each phase is read on its own.
• Weak: Redrawing the aimline lower when the student falls behind. Better: Keep the aimline and change instruction. Only the IEP team changes the goal.
• Weak: A trend line from 3 points. Better: Wait for 6 to 8 points, or use the four-point rule until then.
• Weak: Mixing measures on one graph, such as accuracy one week and rate the next. Better: One graph per goal, one unit per graph.

Graphing different kinds of goals

The same steps work for any goal with a number. For goals that should go down, such as call-outs per class measured with frequency recording, the aimline slopes downward from the baseline to the target. For task analysis goals, plot steps completed independently. For percent goals, keep the denominator the same every session so points can be compared. The measurement methods pages explain each unit.

Tools

A paper graph works: copy a blank grid, draw the axes once and add a point each week. A spreadsheet works too, with weeks in one column, scores in the next and the aimline in a third. The free IEP data sheets record the scores you will plot. If you graph many students, IEP Atlas Pro draws each goal's graph from the session data as you enter it.

Frequently asked questions

Use it in IEP Atlas

• Goal line in the IEP glossary
• Progress monitoring in the IEP glossary
• Measurement methods
• Rate per minute measurement guide
• Frequency data sheet

Related guides

• IEP progress monitoring: how to track, graph and report goal progress
• Decision rules: the four-point rule and trend analysis
• IEP progress report examples: weak vs strong, tied to graphed data
• How often to monitor IEP progress, and with what data
• IEP progress report comment examples

Sources

1. Progress Monitoring: Data & Goal Setting, National Center on Intensive Intervention

Written and checked by the IEP Atlas editorial team under our editorial policy. This guide describes general practice and federal rules. It is not legal advice; your state may add requirements, and the IEP team makes the decisions for each student.