The last couple years I have seen an increase in questions asked to me regarding what various numbers mean that parents receive from the school or from test printouts. When I worked in the schools years ago, I got questions from both parents and teachers. While my child was in public school I too got those vague print-outs with numbers. However, I knew what they meant. Sadly many parents do not because they were given no additional information than the score print out. And, of course, most are not trained in educational testing nor statistics. Thus, after helping the last two parents navigate their initial special education referrals and clarifying what those scores mean, I decided it was time to write a blog explaining it all.
First, I’m going to start with DRA’s. DRA’s are developmental reading assessments and are the most common reading scores seen at the preschool and elementary level. DRA’s range from 1 to 80 and without any other context are meaningless to parents. However, what many are unaware is that DRA’s have a corresponding guided reading level (letters A-Z) and approximate grade level (pre-K through 8th). In addition, many early readers sent home from schools or picked up from public libraries will often have a DRA or Guided Reading Level on their back cover. Other corresponding terms or scores used are Fountas & Pinnell (letters A-V), Lexile (BR-70 to 1385), Scholastic Reading Inventory (also called SRI, is Scholastic’s own letter rating system of A-Z) and Reading Recovery (1-40). In isolation, all of these scores are meaningless to parents unless they are provided with a further explanation of what the age or grade equivalent is or how to find that information.
Here are some important charts to help explain DRA, Lexile, SRI, Fountas & Pinnell, age equivalents, and grade equivalents for reading:
- http://www.riverview.wednet.edu/curric/elemglance/readingbenchmark/DRA-BookLevelChart.pdf is a very simple and only showing DRA with guided reading level by grade level.
- A-Z Reading A-Z has an even better chart: https://www.readinga-z.com/learninga-z-levels/level-correlation-chart/ . Their chart has DRA, age equivalents, grade equivalents, guided reading, reading recovery, Fountas & Pinnell, and Lexiles all in comparison. This makes it very easy for parents and teachers to go compare the different types of scores available.
- Scholastic has their own chart http://teacher.scholastic.com/products/guidedreading/leveling_chart.htm only showing their reading level system with Lexile and DRA comparison.
- Lexile has written their own chart comparing Lexile ranges to various grade levels and explaining what a Lexile is here: https://lexile.com/about-lexile/grade-equivalent/grade-equivalent-chart/ .
The next area of confusion relates to percentile ranks and standard scores. These two are often reported side by side. Since there is no explanation of what a standard score is many parents just look at the percentile rank and mistakenly read it as a percent mastery which it is not. Percentile rank is not percent mastery but rather a proportion of a distribution that a score is greater than. For example if a student had a percentile rank of 50, it would not mean they have 50% mastery of material but rather it means that 50% of the scores on that same test scored below your score. In fact, a 50th percentile rank is average, the middle of the continuum. A 100 standard score has a 50th percentile rank. Percentile ranks fall on a continuum of 1 to 100 and are used solely to quickly compare one score to others on the distribution of scores. This is why on some group tests like the ITBS, SAT-10, COGAT, and ACT you will see percentile ranks for state, national, and school (district or local) and often times the percentile rank will vary because the distribution of scores between those 3 groups is different. It should be noted that a percentile rank between 25 and 75 is considered average. Percentile rank is just a system of ranking, it is not denoting a mastery level.
If you want to learn more specifically on percentile rank try these resources:
- Area Educational Agency 267 has a simple explanation: https://www.aea267.k12.ia.us/assessment/different-types-of-data-and-scores/percentile-ranks/
- Springer School & Center has a great explanation and graph: http://www.springer-ld.org/blog/mmulcahey/09/20/2013
- Study.com has a lesson on this topic: http://study.com/academy/lesson/percentile-rank-in-statistics-definition-formula-quiz.html
- College Board has a chart showing the percentile ranks for each possible SAT score: http://media.collegeboard.com/digitalServices/pdf/research/SAT-Percentile-Ranks-2012.pdf
- ACT has a chart showing the percentile ranks for each possible ACT score: http://www.actstudent.org/scores/norms1.html
- Pepperdine University has a psychometric conversion table so you can convert standard scores, percentile ranks, scaled scores, and z-scores: http://faculty.pepperdine.edu/shimels/Courses/Files/ConvTable.pdf
Now that percentile ranks have been explained let’s get back to those standard scores which are often reported along with them. Standard scores are most often seen in individualized testing (IQ or achievement) such as within special education reports or for gifted testing. However, when they are reported in a table without any additional explanation, the number is meaningless to the parents. I have seen lots of reports from the schools where the report is filled with tables listing standard score and percentile ranks but no explanation for the parents. Thus, the tables get misread or ignored because they are confusing. If the parent is lucky, they’ll get an explanation in their ARD (IEP or M-team) meeting. Sadly, many aren’t given an explanation besides their student qualifies for services or they don’t. From our own experience, our son’s gifted report was filled with tables but no explanation of those numbers. In our meeting, we were given a brief explanation. However, as a former practicing school psychologist I knew exactly what those numbers all meant. Most parents don’t have that knowledge when they go into the meetings or read the report.
So what do parents need to know? They need to know that a standard score is a norm-referenced score. Standard scores are used so that norm-referenced tests (IQ or achievement tests) can place scores for any individual on any test or subtest on to the same standard scale in order for comparisons to be made. When a standard score or a scaled score is reported, it will often contain a mean and standard deviation listed. These are important for when comparing scores on a normal curve and comparing with percentile ranks. Most IQ and achievement tests have a mean standard score of 100 and a standard deviation (SD) of 15. This means the score of 100 is going to be at the 50th percentile rank. And if you go 1 standard deviation of the mean (+ or – 15 points), you will still be in the average range (standard score of 85-115 is average). Although most schools actually list average as standard scores 90-110, statistically speaking average is 85-115. Schools will often report scores of 80-89 as low average and scores of 110-119 as high average. Many schools will not accept students for gifted education unless scores are above 130 or 145 pending district and state, although some will use 120. As for special education, students with standard scores below 70 often qualify as students with cognitive disabilities or intellectual disabilities pending the state’s lingo used. Students with average cognitive scores (85-115) but sub average achievement scores (a score below 85) might meet eligibility for specific learning disability. Again, each state and district within a particular state has their own lingo and nuances for qualifying for any special education services. In addition to standard scores being reported on what is called a normal curve, T-scores, scaled scores, stanines, Z-scores and percentile ranks are also plotted on the same curve which allows very easy comparison. The normal curve is also known as normal distribution and bell-curve.
The following resources are beneficial for understanding standard scores and comparing them with percentile ranks, stanines, Z-scores, T-scores, and scaled scores:
- The National Association of School Psychologists (yes, I’m member of this group) has a great handout for understanding standard scores: http://www.nasponline.org/communications/spawareness/testscores.pdf
- Virginian University put this together for helping explain the WJ-III but it also offers great information for parents to better understand their child’s standard scores on any measure: http://faculty.virginia.edu/PullenLab/WJIIIDRBModule/WJIIIDRBModule7.html
- Wrightslaw is a special education advocacy group and they have short handout for parents to better understand standard scores: http://www.wrightslaw.com/advoc/articles/bellcurve.pdf
- A pocket guide with a diagram and quick explanation: http://p4k.s3.amazonaws.com/day_2/Pocket_Guide.pdf
- Easy bee has printable normal curve graphs showing IQ, ACT, SAT, stanine, Z-score, and percentile rank for easy reading: http://www.myeasybee.com/blog/free-easybee-printable-standard-scores-chart-for-parents/
I hope this blog and resources linked will help you understand your child’s scores. Feel free to print off or share any of the linked charts if it will be helpful for you or other parents. My goal is that all parents feel educated and knowledgeable about the data they receive on their child from any source–school district testing, private testing, or college placement testing. Also remember, the data you are looking at is just one snapshot of your child’s performance and not the complete picture.