title: Differential item functioning in the beck depression inventory.
abstract: BACKGROUND
  There are several studies showing the presence of Differential Item Functioning (DIF) in some items of the Beck Depression Inventory (BDI), when comparing men and women. The presence of a large number of items with DIF in BDI is a severe threat to the validity of measurement of the intensity of depressive symptoms obtained by Item Response Theory (IRT) and to the conclusions based on the scores derived from the items with or without DIF.
  
  
  OBJECTIVE
  The objectives of this study were to identify these items from the BDI, adjust the IRT model for embarrassing items (model 2), which accommodates items with the presence of DIF, and compare these results with the fit of the traditional two-parameter logistic IRT model (model 1).
  
  
  METHODS
  The results obtained with the both models were compared.
  
  
  RESULTS
  Items with DIF were: sadness, feeling of failure, dissatisfaction, guilty, punishment, crying, fatigability and loss of libido. The results of the adjustment of the two models are similar in discrimination, gravity (except for items with DIF), and in the calculation of scores for individuals. Nevertheless, model 2 is beneficial because it shows the differences in gravity of depressive symptoms for groups evaluated, thus providing more information to the researcher on the study population.
  
  
  CONCLUSIONS
  This model, which has a broader scope in terms of target population, may be a good alternative to the identification and follow-up of individuals with potential depression.
authors: Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil.
authors: Stela Maris de Jezus
authors: SM
authors: Castro
authors: Universidade de São Paulo, São Carlos, SP, Brasil.
authors: Mariana
authors: M
authors: Cúri
authors: Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil.
authors: Vanessa Bielefeldt Leotti
authors: VB
authors: Torman
authors: Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil.
authors: João
authors: J
authors: Riboldi
mesh_terms: D000328:Adult; D003863:Depression / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D015233:Models, Statistical