3di

Thank you Recombinantsocks. I have spoken to the assessment centre, and they have told me its a parent interview, and yes computerised. My son doesn't need to be there. He is having 5 observations, over 5 weeks, and they will use this in conjunction with the 3Di assessment to get the final outcome. 

There are a number of threads here in the forum on the subject - you are not the first to ask about this..

community.autism.org.uk/.../3di

Apparently it is "a new computerised interview, the Developmental, Dimensional and Diagnostic Interview (3Di) www.bjmp.org/.../autistic-spectrum-disorders-assessment-and-intervention-children-and-adolescents

I haven't heard of this before - the article in bjmp may be some help for you. Generally the advice for these tests is that the child needs to be as relaxed and happy as possible and for them to answer the questions without fretting about what answer is right.