What is a "standard deviation" ?

Deborah621

I see this a lot on here when describing how delayed a child is. So far with EI they have only told me how many months delayed he is in certain areas. Thanks.

lazysusan

There is a bell curve.  most fall in the middle of the curve with some children being on the very front of the curve and others being on the other end.  Placing a line through the middle of the curve 50% are above 50% are below.  The curve is then divided into units one unit below the 50% is one standard deviation below (-1.00).  2 units below 50% is 2 standard deviations below.  1 unit above is 1.00, 2 units above is 2.00.  In New York state (the other states are probably similiar) 0 to -1.00 is considered within age expected limits, -1.00 to -1.5 is considered a mild delay, -1.5 to -2.00 is considered a moderate delay, over -2.00 standard deviations is considered a severe delay.  I hope this helps.  You will also find age equivalents, percentiles and other ways to describe a delay.

Anlo

PPsummed it up well. Just to add (googled to double check my stats), about 68% of cases in a normal bell curve are within one standard deviation from the middle (also called the mean), so from -1.00 to 1.00. About 95% of the values fall within two standard deviations of the mean (-2.00 to 2.00).

ali0608

As a stats teacher, I'm happy to report that everything that has been said here is correct.  I also appreciate seeing my subject being used in real life. 

 

kel716

ali0608:

As a stats teacher, I'm happy to report that everything that has been said here is correct.  I also appreciate seeing my subject being used in real life. 

 

Agreed!

torrey111

This is such a great ? and thanks for asking it...I've been wondering the same thing!

kyethra

Additionally one may use standard deviations on different types of IQ to determine issues.  For example, I have a large split where my verbal IQ is two standard deviations above my performance IQ and this is characteristic of a learning disability I have-- this documentation of that allowed me accommodation like longer test times in college, and the length of test times was determined by my scores and the deviation.

mollybloom

EI uses the standard deviations to determine elegibility for services. In my county, a child needs to be two standard deviations below average to qualify for services.