Converting standard scores to percentile rank
- If the evaluation test scores are reported in standard score, the link above will tell you how to convert that to a percentile rank. The 50th percentile is average – meaning that half the people will score above, and half the people will score below. It is important to see the scores in percentile rank, and also to plot on a bell curve to visually see where the strengths and weaknesses are. Students with learning disabilities typically tend to have a wide scatterring of scores, meaning some will be in a higher range and some will be in a lower range. For example, my son was in the 99th percentile for verbal ability, but in the 4th percentile for reading. This is a huge discrepancy.
- The majority of people (68% of the population) will score around the 50th percentile, and this is considered average. This is the peak of the bell curve. 34% of the population will score within 1 standard deviation above the 50th percentile, and 34% of the population will score within 1 standard deviation below the 50th percentile.
- 28% of the population will fall between 1 and 2 standard deviations, so 14% of the population will be between 1 and 2 standard deviations above the 50th percentile, and 14% of the population will be between 1 and 2 standard deviations below the 50th percentile.
- So a total of 96% percent of the population will fall within 2 standard deviations above (48%) the 50th percentile and 2 standard deviations below (48%) of the 50th percentile.
- Only 2% of the population will fall more than 2 standard deviations above the 50th percentile, and only 2% of the population will fall more than 2 standard deviations below the 50th percentile.
- This is not an endorsement for Reading Naturally, I just thought the reading fluency chart was a good tool for parents to guage their child’s progress as it breaks down the rates by grade for fall, winter, and spring, as well as giving the percentile ranking. It is also important to know how the words correct per minute (wcpm) was measured. If it was measured using a list of words (particularly if memorized “sight” words), that will not reflect the true rate at which the child is reading
- In a nutshell, the rich get rich and the poor get poorer. Read the full article here.
- Watch a video clip of Dr. Keith Stanovich explain the Matthews Effects.
Wrightslaw’s Tests and Measurements for the Parent, Teacher, Advocate & Attorney
- An in-depth explanation of how to understand the “facts” of the various evaluations and by using the test scores, how to determine if educational progress has been made or if regressions has occurred. Regression in this instance means that the child’s progress has stalled or has been minimal while his peers are progressing. In effect, the child is falling further behind his peers and has received very little to no educational benefit from his individualized education plan.