title: The reliability and validity of the Questionnaire - Children with Difficulties (QCD).
abstract: BACKGROUND
  The aim of this study was to evaluate the reliability and validity of the Questionnaire-Children with Difficulties (QCD), which was developed for the evaluation of children's daily life behaviors during specified periods of the day.
  
  
  METHODS
  The subjects were 1,514 Japanese public elementary and junior high school students. For the examination of reliability, Cronbach's alpha was calculated to assess the internal consistency of the questionnaire. With regard to validity, correlation coefficients were calculated to examine whether QCD scores correlated with those of the ADHD-Rating Scale (ADHD-RS) and the Oppositional Defiant Behavior Inventory (ODBI).
  
  
  RESULTS
  Cronbach's alpha coefficient for the total score of the QCD was .876. The correlation coefficients of the QCD score with ADHD-RS and ODBI scores were -.514 and -.577, respectively.
  
  
  CONCLUSIONS
  The internal consistency and validity of the QCD were demonstrated. The QCD is a reliable and valid instrument for evaluating daily life problems for children during different time periods of the day.
authors.affiliation: Department of Child and Adolescent Psychiatry, National Center for Global Health and Medicine, Kohnodai Hospital, Ichikawa, Japan. usami.masahide@hospk.ncgm.go.jp.
authors.forename: Masahide
authors.initials: M
authors.lastname: Usami
authors.forename: Daimei
authors.initials: D
authors.lastname: Sasayama
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Sugiyama
authors.forename: Nana
authors.initials: N
authors.lastname: Hosogane
authors.forename: Soo-Yung
authors.initials: SY
authors.lastname: Kim
authors.forename: Yushiro
authors.initials: Y
authors.lastname: Yamashita
authors.forename: Masaki
authors.initials: M
authors.lastname: Kodaira
authors.forename: Kyota
authors.initials: K
authors.lastname: Watanabe
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Iwadare
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Sawa
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Saito
references.citation: J Am Acad Child Adolesc Psychiatry. 2000 Dec;39(12):1468-84
references.pmid: 11128323
references.citation: Brain Dev. 2010 Sep;32(8):609-12
references.pmid: 19828270
references.citation: Child Adolesc Ment Health. 2008 Sep;13(3):140-147
references.pmid: 32847173
references.citation: Psychol Bull. 2005 Jul;131(4):483-509
references.pmid: 16060799
references.citation: J Child Adolesc Psychopharmacol. 2009 Dec;19(6):709-18
references.pmid: 20035589
references.citation: J Child Psychol Psychiatry. 2009 May;50(5):544-61
references.pmid: 19432681
references.citation: Clin Ther. 2006 Nov;28(11):1892-908
references.pmid: 17213010
references.citation: Annu Rev Med. 2002;53:113-31
references.pmid: 11818466
references.citation: Eur Child Adolesc Psychiatry. 2004 Jun;13(3):185-90
references.pmid: 15254847
references.citation: J Am Acad Child Adolesc Psychiatry. 1998 Mar;37(3):305-13
references.pmid: 9519636
references.citation: Child Adolesc Psychiatry Ment Health. 2008 Oct 28;2(1):31
references.pmid: 18957105
references.citation: Eur Child Adolesc Psychiatry. 2010 Feb;19(2):83-105
references.pmid: 19633992
references.citation: Brain Dev. 2008 Jun;30(6):410-5
references.pmid: 18226867
references.citation: Prev Chronic Dis. 2006 Apr;3(2):A52
references.pmid: 16539793