title: Psychometric properties and validation of Portuguese version of Ages & Stages Questionnaires (3rd edition): 9, 18 and 30 Questionnaires.
abstract: BACKGROUND
  The essential underlying foundations of Early Intervention (EI), in which parents/family play a critical role in their child's development, leads us to conclude that their contribution assessing early detection of problems is fundamental. The Ages & Stages Questionnaires (ASQ) is a standardized screening instrument that has been successfully studied in different countries and cultures.
  
  
  OBJECTIVE
  Translate and study the psychometrics proprieties of the Portuguese version of the 9, 18 and 30month questionnaires of the Ages and Stages Questionnaires, 3rd edition (ASQ-3).
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Validity and reliability were studied in a sample of 234 parents of children within 9, 18 and 30months.
  
  
  RESULTS
  The results indicated that the questionnaires had good internal consistency, strong agreement between observers and between observations with two weeks interval, and strong Pearson product-moment correlation coefficients between the overall and the total for each domain. The cutoff points (i.e. 2 standard deviations below the mean domain score), that identifies children who should receive further referral for more comprehensive assessment, were close to those determined in the original ASQ-3 psychometric studies. Cronbach's alpha ranging from .42 to .70 and Pearson's r values varies from .22 to .60.
  
  
  CONCLUSIONS
  Although some weaknesses were noted in psychometric qualities analysis, it can be concluded that the ASQ-PT of 9, 18 and 30months of age fulfills the requirements of a screening tool validated for the Portuguese population.
  
  
  CONCLUSIONS
  To allow the early identification of children with developmental problems.
authors.affiliation: Escola Superior de Saúde Jean Piaget V. N. Gaia, Instituto Piaget, Portugal. Electronic address: sonia.lopes@gaia.ipiaget.pt.
authors.forename: Sónia
authors.initials: S
authors.lastname: Lopes
authors.affiliation: Centro Integrado de Saúde Desenvolvimento Educação e Cultura, Rua Padre António Caldas, n° 1281, Oliveira do Castelo, 4810-246 Guimarães, Portugal. Electronic address: to.patriciameireles@gmail.com.
authors.forename: Patrícia
authors.initials: P
authors.lastname: Graça
authors.affiliation: Centro Integrado de Saúde Desenvolvimento Educação e Cultura, Rua Padre António Caldas, n° 1281, Oliveira do Castelo, 4810-246 Guimarães, Portugal. Electronic address: l_salete_t@hotmail.com.
authors.forename: Salete
authors.initials: S
authors.lastname: Teixeira
authors.affiliation: Instituto de Educação (IE), Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal. Electronic address: serrano@ie.uminho.pt.
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Serrano
authors.affiliation: Center on Human Development, University of Oregon, 901 E 18th Ave., Suite 139, Eugene, OR 97403-5253, United States. Electronic address: jsquires@uoregon.edu.
authors.forename: Jane
authors.initials: J
authors.lastname: Squires
mesh_terms: D002657:Child Development; D002675:Child, Preschool; D018479:Early Intervention, Educational; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D011174:Portugal; D011594:Psychometrics / Q000379:methods; D011795:Surveys and Questionnaires
keywords: Ages and Stages Questionnaires; Early intervention; Psychometry; Screening; Validation