Editorial - allegiance revisited

It is now ten years since Luborsky et al. (1999) published their classic paper on the research’s therapy allegiance, indicating that measures of this explained 69 per cent of the variance in outcomes in comparative studies of psychological therapies. Indeed, apparent differences in outcome between therapies may all but disappear when account is taken of researcher allegiance (Elliot et al., 2004; Luborsky et al., 2002; Robinson, Berman, & Neimeyer, 1990). What, then, is the purpose of a further collection of papers on a topic that has been described as ‘by now a well-established phenomenon in psychotherapy research’ (Jacobson, 1999)? Firstly, the extent of allegiance effects has been disputed, and various questions concerning researcher allegiance remain unanswered.