title: Issues related to obtaining intelligence quotient-matched controls in autism research.
abstract: BACKGROUND
  Intelligence Quotient (IQ) is considered to be an index of global cognitive functioning and has traditionally been used as a fulcral measure in case-control studies in neuro-developmental disorders such as autism.
  
  
  OBJECTIVE
  The aim is to highlight the issues of "matching for IQ" with controls in autism research.
  
  
  METHODS
  Percentile scores on the Coloured Progressive Matrices of 20 children with autism in the age range of 5 to 12 years have been graphically compared with 21 age matched typically developing children.
  
  
  CONCLUSIONS
  The percentile scores of the so-called high functioning children with autism from special schools were well below that of typically developing children. There are many challenges when using IQ in case-control studies of autism. Alternative approaches need to be considered.
authors.affiliation: St. John's Medical College Hospital, Bengaluru, Karnataka, India.
authors.forename: Vanitha S
authors.initials: VS
authors.lastname: Rao
authors.affiliation: St. John's Medical College Hospital, Bengaluru, Karnataka, India.
authors.forename: Vijaya
authors.initials: V
authors.lastname: Raman
authors.affiliation: St. John's Medical College Hospital, Bengaluru, Karnataka, India.
authors.forename: Ashok V
authors.initials: AV
authors.lastname: Mysore
keywords: Autism spectrum disorders; case-control study; intelligence quotient; nonverbal