Severity Terminology: Sharon’s Attempt at Simplifying Terms:
Average- within 1 standard deviation above or below mean (16th percentile
rank and up, although I would call the 16th percentile ‘borderline’/ low
average)
Mild- within 1 to 1.5 standard deviations below the mean (I do not use this
term often, but CELF-Preschool uses it to refer to a range from 8th
percentile to 16th) Personally, I often skip this term and go to
moderate/ ‘significant’ terminology after 16th percentile.
Moderate- between 1.5 to 2 standard deviations below mean (usually use
scores lower than 16th percentile down to 4th percentile rank)
Severe- two deviations below the mean and lower (CELF- Preschool uses
2nd percentile rank and down, however I would use 3rd percentile rank and
down)
Profound- three standard deviations below the mean and lower (1st
percentile and lower)
I generally don’t use this term
Nancy’s terminology/severity ratings.
Note - I’ve removed “15 to 25 is also considered a borderline delay” from
my recent reports based on the feedback from the team.
A percentile ranking is not a percentage (%); that is, it is not a measure of
accuracy scored out of 100. A percentile ranking is a standardized test
score that allows the child’s performance on a specific task(s) to be
compared to 99 same-age peers with 1 being the weakest and 100 being
the best performance. A percentile ranking between 16 and 84 is
considered to be within normal limits; however, 15 to 25 is also considered
to be a borderline delay. Percentile rankings of 7 to 15 represent a mild
delay; 2 to 6 is a moderate delay; < 2 is a severe delay.
I also included the following severity rating scales from two common
standardized language tests for our discussion.
Clinical Evaluation of Language Fundamentals – 4th Edition (CELF-4)
Core Language
Score & Index
Scores
Classification
Relationship to
Mean
Percentile
Ranking
115 and above
Above average
+1 SD and
above
84 and
above
86 to 114
Average
Within + or – 1
SD
16 to 83
78 to 85
Marginal/Borderline/Mild Within -1 to –
1.5 SD
7 to 15
71 to 77
Low range/Moderate
Within -1.5 to 2 SD
2 to 6
70 and below
Very low range/Severe
-2 SD and
below
<2
Peabody Picture Vocabulary Test – 4th Edition (PPVT-4)
Standard
Score
Classification
Relationship to
Mean
Percentile
Ranking
130 and above Extremely high score
+2 SD and above
98 and above
115 to 129
Moderately high
score
+ 1 to +2 SD
84 to 97
100 to 114
High average
Avg. To +1 SD
50 to 83
85 to 99
Low average
-1 SD to Avg.
16 to 49
70 to 84
Moderate low score
-2 SD to -1SD
2 to 15
69 and below
Extremely low score
-2 SD and below
<2
From the parent report in the PPVT (definitions):
A standard score shows how your child’s raw score differs from the average by
converting the raw score to a score on a new scale. A standard score of 100 is
average for a student’s age or grade. Standard scores higher than 100 are above
average, and those lower than 100 are below average. For example, if your child’s
standard score is 110, this indicates a high average performance on the test. If
the score is 89, that indicates a low average performance.
A percentile indicates the percentage of students in the group tested who
performed at or below your child’s score. For example, if your child’s percentile is
64, this means that he or she performed as well or better than 64% of the children
of the same age or in the same grade. (p. 198)
Trent says: We had talked about adapting the terminology presented
by Wayne Secord in Pathways to Excellence. I must say it appeals to
me ... I will post it here:
Standard Scores and Educational Performance Ranges
Above Educational Average → Standard score 115 and above (+1 SD above the
mean)
Average Educational Range → Standard score 86 to 114 (within +/-1 SD of the
mean)
Marginal Educational Range → Standard score 79 to 85 (within -1 to -1.5 SD of the
mean)
Low Educational Range → Standard score 71 to 78 (within -1.5 to -2 SD of the
mean)
Very Low Educational Range → Standard score 70 and below (-2 SD below the
mean)