Generally, people with autism can be divided into 3 groups, by age 5 or 6 years. Approximately, 50% of people with autism are also mentally retarded both in verbal and non-verbal skills. 25% have normal non-verbal intelligence but poor language skills. 25% have normal language and non-verbal skills. If the child is young, it is very difficult to determine which of these three groups he/she will fall into.
The I.Q. scores as measured on cognitive tests are important in assessing children with autism. However, it is important not to give too much significance to a score on a test. Because the problem with the autistic children is that they may have very good cognitive skills, but are unable to use them.
The ability of the person to function independently in society is more important than his intellectual fucntioning. Social adaptive skills should give more importance. Because it doesn't matter whether you are a smart person but you cannot get across the street or if you know calculus but cannot make change.
It is crucial to focus on the development of social or adaptive rather than academic skills if the goal is to help autistic persons be integrated into society.