No, I think you are figuring a percentage based on the age score and his age....
OK, first, in general he is saying that in terms of social communication, he is at a low end of what would be officially delayed in his opinion. Now, as a parent, are you comfortable with that big of a delay?? I assume not. And given the comparison to other test scores, is this a much lower score than other areas of development?? If so, that is the important thing to note. That he is really struggling in this area comparatively speaking.
But officially,
On standardized tests, a child(or whoever takes whatever test) gets a RAW score. That score is the actual score they get on the test (number right, or number wrong or whatever depending on the test)
That Raw Score is converted to a Standard Score, in the case of these tests, based on his actual age on the day of testing. The standard scores are based on a "normal distribution curve" simply, the mean/average score is 100. 1 SD above and below the mean are standard scores of 85-110 (about 68% of those who took the test fell within that range).... It only means they have that score on that kind of test in that area being tested...It does not mean that on other kinds of tests he will get the same. In fact it can be useful to compare one kind of test to another, and at times it is not.
IQ is an example of using a standard score... 100 is "average" 85-110 clearly within average range... and below that is still "average" for quite a way...but we start to say low average etc. Different people will say 75 is the cut off for below average scores, some say 73, some say 70 but you get the idea.
A test in an area like language when given a standard score then can be compared to the IQ score in this way... they can say, hey he has an IQ/ability of 90 but his language understanding is testing at a standard score of 65. Pretty significant difference. Well, that could mean there is a problem because he is not functioning to his potential. A language learning disability.
[Of course that means one would have to buy into IQ being a truly valid representation of ability. But that is another discussion. (For some kids it is just not a good measure in my humble opinion)]
Say his Standard Score was 70, that is 2 SD below the mean of 100 and most use this as a clearly below normal (it would be the 2nd percentile rank which means of 100 people taking the test, 98 would do better than that score.... do you see how that is different from a percentage?)
I am awful with statistics so I am sure I am much worse at explaining it.
There are limitations to using grade or age scores. They are not used frequently but are more commonly in very young kids or very very delayed kids because people can relate to ages, but the problem is... then people panic and think that the child's overall development is at that age.
TESTING TERMS click this to see the normal distribution of standard scores and definitions of test terms...
Grade Equivalent Score A child's actual performance on a test -- the number answered correctly and termed a "raw score" -- may be converted to a Grade Equivalent score. The Grade Equivalent score expresses the grade level of students who on average get that raw score. So, for example, if a 3rd grade child who is tested achieves a raw score of 10 points, and children near the end of 1st grade (at the 9th month) on average earn a raw score of 10 points, the 3rd grade child will be assigned a GE score of 1-9 (sometimes written 1.9). "Grade Equivalent scores are based on the assumption that it is helpful to define progress in terms of the grade-level at which an average student attains a given level of knowledge or skill."
This information can be very interesting, but the parent should not conclude that the 3rd grade child has math skills that are identical to those of a student at the 1-9 level. Let's say the child gets a few addition problems correct, a couple of subtraction problems correct, but not subtraction with regrouping, and several single digit multiplication problems correct. The testing shows some skills are lacking, but shows some good 2nd and 3rd grade math skills as well, beyond those expected for a 1st grade child.
Parents need to use caution with Grade Equivalent scores. They present an overall approximation of grade level achievement, but it is important to analyze the error pattern to fully understand strengths and weaknesses.
GE score differences from one school year to the next are less meaningful at upper grade levels, since students do not make as much steady progress in skill mastery as they do in lower grade levels.
Standard Scores are converted to GE scores with tables provided by the test manufacturer. The GE score permits the examiner to state the approximate grade level at which the child is performing in a specific skill or on a certain test. Recently fallen out of favor with educational testing researchers, GE scores can still provide some useful information if it is understoodthat a single GE score does not mean the child is working at that grade level in all areas. It most certainly does not mean that the child should be placed at the corresponding grade level, unless there is solid supporting documentation.
Age Equivalent Score
The Standard Scores can also be statistically converted to show the typical age of the norm group that obtained a similar score. Like the Grade Equivalent Scores, Age Equivalent Scores permit comparison of the child's scores with those of others who were tested on the same test. Age Equivalent Scores have the same limitations as Grade Equivalent Scores.
He should have included more than age scores, they can cause great concern because there is a range of normal and he is saying that in his opinion he is on the borderline of that normal range and delayed. It would be easier to see that if he said he fell in the 25th percentile rank for example....you could then see that of 100 kids taking the test at that age, 25 would have the same or lower scores than your child.
Did they report the scores in any other format?
sorry I am not a good teacher in this... anyone else who can explain better feel free...