busker wrote: > > I'm completely new to statistics but am putting together a > customer satisfaction survey, thanks to which I am daily > becoming fascinated by my whole new world of Means and > Medians and Variabilities and Variances, and so forth. I am > told that certain "duplicate" questions are sometimes put > in to test the consistency/'truthfulness' of a respondent's > answers,and that these 'check' questions are called split > half coefficients (or thereabouts). But i find no reference > in the text books I'm poring over. Can anyone enlighten me? > I hope I've explained myself correctly and, if not, that I > cn be pointed on the right track: I know how vital it is to > have the correct terms in this business. > Chris: The split-half coefficient was invented in the early years of the 20th century as a way of checking the internal consistency of a measurement scale. One takes half the items in a scale (say the odd numbered items) and scoresd their total, and then correlates this with the score on the other half of the scale. An adjustment is then made to correct for the shortened length of the scale by taking only half the items. Nobody bothers with this any more; the procedure has been superseded by the more convenient Cronbach's alpha coefficient. Neither of these statistics is directly concerned with the issue you raise, namely that of having repeated items in order to check whether an individual respondent is answering the same question consistently. You won't find these concepts discussed in books on basic statistics. Look instead for books on educational and psychological measurement. You local university library should be able to help. Paul Gardner
begin:vcard n:Gardner;Dr Paul tel;cell:0412 275 623 tel;fax:Int + 61 3 9905 2779 (Faculty office) tel;home:Int + 61 3 9578 4724 tel;work:Int + 61 3 9905 2854 x-mozilla-html:FALSE adr:;;;;;; version:2.1 email;internet:[EMAIL PROTECTED] x-mozilla-cpt:;-29488 fn:Dr Paul Gardner, Reader in Education and Director, Research Degrees, Faculty of Education, Monash University, Vic. Australia 3800 end:vcard
