title: Validation of self-directed learning instrument and establishment of normative data for nursing students in taiwan: using polytomous item response theory.
abstract: BACKGROUND
  Little research has investigated the establishment of norms for nursing students' self-directed learning (SDL) ability, recognized as an important capability for professional nurses. An item response theory (IRT) approach was used to establish norms for SDL abilities valid for the different nursing programs in Taiwan.
  
  
  OBJECTIVE
  The purposes of this study were (a) to use IRT with a graded response model to reexamine the SDL instrument, or the SDLI, originally developed by this research team using confirmatory factor analysis and (b) to establish SDL ability norms for the four different nursing education programs in Taiwan.
  
  
  METHODS
  Stratified random sampling with probability proportional to size was used. A minimum of 15% of students from the four different nursing education degree programs across Taiwan was selected. A total of 7,879 nursing students from 13 schools were recruited. The research instrument was the 20-item SDLI developed by Cheng, Kuo, Lin, and Lee-Hsieh (2010). IRT with the graded response model was used with a two-parameter logistic model (discrimination and difficulty) for the data analysis, calculated using MULTILOG. Norms were established using percentile rank.
  
  
  RESULTS
  Analysis of item information and test information functions revealed that 18 items exhibited very high discrimination and two items had high discrimination. The test information function was higher in this range of scores, indicating greater precision in the estimate of nursing student SDL. Reliability fell between .80 and .94 for each domain and the SDLI as a whole. The total information function shows that the SDLI is appropriate for all nursing students, except for the top 2.5%. SDL ability norms were established for each nursing education program and for the nation as a whole.
  
  
  CONCLUSIONS
  IRT is shown to be a potent and useful methodology for scale evaluation. The norms for SDL established in this research will provide practical standards for nursing educators and students in Taiwan.
authors.affiliation: 1PhD, RN, Associate Professor, Department of Nursing, National Taipei University of Nursing and Health Sciences 2MSN, RN, Professor and Director, Graduate Institute of Allied Health Education, National Taipei University of Nursing and Health Sciences 3MA, Lecturer, Language Center, Chang Gung University 4PhD, Professor, Department of Health Care Management, National Taipei University of Nursing and Health Sciences.
authors.forename: Su-Fen
authors.initials: SF
authors.lastname: Cheng
authors.forename: Jane
authors.initials: J
authors.lastname: Lee-Hsieh
authors.forename: Michael A
authors.initials: MA
authors.lastname: Turton
authors.forename: Kuan-Chia
authors.initials: KC
authors.lastname: Lin
mesh_terms: D000293:Adolescent; D000328:Adult; D003697:Delphi Technique; D004506:Education, Nursing / Q000379:methods*; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D015402:Nursing Education Research; D015397:Program Evaluation; D011380:Programmed Instructions as Topic / Q000592:standards*; D011594:Psychometrics / Q000295:instrumentation*; D013338:Students, Nursing / Q000523:psychology* / Q000706:statistics & numerical data; D013624:Taiwan; D055815:Young Adult