Percentage or Percentile?
“Do you know the difference between percentage and percentile? If not, you’re probably writing ineffective IEPs and perpetuating the achievement gap.”
That quotation launched Jon Paul Burden’s morning keynote at the Nebraska Transition Conference last month. I can’t stop thinking about it. His question was followed by explanations and examples. I’d like to share my takeaways with you.
First, the difference:
—> Percentage - a figure out of 100 of the quantity measured. For example, 60 percent on a test means the student had 6 correct out of 10 problems OR 60% could refer to time. If data were collected for 10 intervals, the student was observed to demonstrate the targeted behavior in 6 of those intervals.
—> Percentile - ranking in the sample. For example 60 percentile on a test would mean that in a group of 100 people who were scored, 59 people scored below and 39 scored above this person.
Which are used in your IEPs?
I usually see percentages. That means we’re using a short term, episodic view of the child’s progress. With percentages, it would be hard to determine whether the child is making progress compared to their peers.
Think about it. When you take your infant or toddler for a wellness checkup, the doctor doesn’t tell you her height and weight based on your doctor-made evaluation or compared to others your doctor examined this month. You get percentiles compared to the national averages for a child that age. Right?
When we send IEP progress reports home, if we report percentages, what do they mean? Sean has a 72% average in math and Samantha can read 90% of second grade sight words. What does that mean about their growth? What if we say Samantha improved 10% over last year. Does that really inform her family - or us -- about her progress in the standard curriculum? Where do they score in comparison with their peers?
Remember that students with IEPs were found eligible for special education services by an IEP team because there was a discrepancy between their performance and the norm for their peers
IDEA requires us (especially since the Endrew F Supreme Court decision) to provide supports and services that are “reasonably calculated” to enable them to make progress in the general curriculum that is “ambitious in light of the child’s unique circumstances.” How can we know whether they are making progress - and how can we partner with families in evaluating progress - if we don’t compare students with their same-age peers?
When we develop IEP goals, what criteria should we use for mastery? Burden shared that in Wyoming he encourages IEP teams to target 40 percentile for any student without a cognitive impairment. He shared that the 40th percentile is the standard for minimal proficiency used by developers of nationally used indexes like Dibels, NWEA and AimsWeb.
By setting a 40 percentile target for an IEP goal, the team is declaring to all teachers, service providers, and the family the intention to close the achievement gap. They may not accomplish it this year, but no one can be faulted for aiming high and falling short. The outcome will likely be much higher than if the target is set low.
In most cases, it will be more ambitious to target 40 percentile on a norm referenced scale rather than 80% on a teacher-made test. And then we won’t have to explain to a family why their conscientious child has a B average and is still “significantly below” standards on the state test. So when we prepare graphs of progress on an IEP goal, there should be a line to indicate that student’s progress, of course. We should also include a target line - where the student would perform if he met minimal proficiency for his grade level (at the 40th percentile).
What do you think?
Do you already use percentiles in your IEP goals? What preparation will team members (professionals and families) need if you start using percentiles instead of percentages?
Contact me if you’d like to talk about how I might support your school district.
