The reliability of a two-item scale: Pearson, Cronbach, or Spearman-Brown?

Rob Eisinga, Manfred te Grotenhuis, Ben Pelzer Department of Social Science Research Methods and Department of Sociology, Radboud University Nijmegen, PO Box 9104, 6500 HE Nijmegen, The Netherlands October 8 2012 To obtain reliable measures researchers prefer multiple-item questionnaires rather than single-item tests. Multiple-item questionnaires may be costly however and time-consuming for participants to complete. They therefore frequently...