Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí hóa học quốc tế đề tài : Understanding Ferguson's δ: time to say good-bye? | Health and Quality of Life Outcomes BioMed Central Letter to the Editor Open Access Understanding Ferguson s 8 time to say good-bye Berend Terluin 1 Dirk L Knol2 Caroline B Terwee2 and Henrica CW de Vet2 Address Department of General Practice and the EMGO Institute for Health and Care Research VU University Medical Centre Amsterdam the Netherlands and 2Department of Clinical Epidemiology and Biostatistics and the EMGO Institute for Health and Care Research VU University Medical Centre Amsterdam the Netherlands Email Berend Terluin - Dirk L Knol - Caroline B Terwee - Henrica CW de Vet - Corresponding author Received 23 February 2009 Accepted 30 April 2009 Published 30 April 2009 Health and Quality of Life Outcomes 2009 7 38 doi 86 1477-7525-7-38 This article is available from http content 7 1 38 2009 Terluin et al licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License http licenses by which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. Abstract A critique of Hankins M How discriminating are discriminative instruments Health and Quality of Life Outcomes 2008 6 36. Background Recently Hankins re- introduced Ferguson s coefficient 8 as an index of discrimination to be distinguished from the well-known measurement properties validity and reliability 1 2 . Hankins presented Ferguson s 8 as a useful index of the degree to which an instrument discriminates between individuals being the ratio of the observed number of between-person differences to the theoretical maximum number possible 1 . The value of 8 varies between 0 no discrimination at all and 1 maximal possible discrimination . The calculation is straightforward and Hankins provided a generalized formula for calculating 8 for questionnaires with dichotomous as .
