Most of the limited body of available research focuses on establishing whether formulation is reliable. A review of research using standardised methods to assess inter-rater reliability in psychodynamic formulations found moderate-to-good agreement (Luborsky & Diguer, 1998). A review of cognitive case formulation research found more mixed results for inter- rater reliability, concluding that it was modest at best (Bieling & Kuyken, 2003, p. The emerging consensus is that reliability is compromised as clinicians move from descriptive to more inferential levels. However, it is unclear whether problems in establishing reliability are due to difficulties in the process, such as the use of heuristics that affect clinical judgement (see Dumont, 1993), or to methodological issues, such as the absence of information available to practitioners in normal service conditions (including the possibility of developing the formulation in collaboration with the client. Moreover, as Bieling and Kuyken (2003) concede, reliability does not imply validity. It is unclear how, if at all, psychologists reliably formulating in the same way relates to the truth or accuracy of the formulation. In addition, formulation could be reliable and valid but have no impact in terms of helping the client conversely, it could be unreliable and invalid but lead to improved outcomes. For these reasons, another strand of research has tried to establish whether formulation leads to positive change for clients. A few studies (Jacobson et al., 1989; Emmelkamp et al.,
1994; Schulte et al., 1992) have attempted to compare individualised treatments (which are, by implication, formulation-driven) with standardised treatments (which are not).
Taken together, the results do not support claims that formulation improves outcomes, although they are all under-powered studies from which little can be safely concluded. Furthermore, it is unclear how closely the individualised conditions in these studies correspond to practice, since they were defined as treatment plans that combined the standardised components more flexibly. Qualitative data from structured interviews suggest that clients are ambivalent about formulation. As finding formulations helpful, encouraging and reassuring, and increasing trust in their psychologist, clients can also experience them as saddening, upsetting, frightening, overwhelming and worrying (Chadwick et al., 2003; Evans & Parry, 1996; Hess. A content analysis of 13 clients experience of formulation in CBT for psychosis indicated that individuals reactions to receiving a formulation were complex, involving apparently opposing emotional and cognitive responses, which changed overtime (Morberg Pain et al., Professional guidelines recommend the use of a formulation based approach when working within multidisciplinary teams (Division of Clinical Psychology, Additionally, service users are reported to value the role of psychologists in teams as offering an alternative perspective to the medical model (Onyett, 2007). Christofides’ (2011) qualitative study of clinical psychologists working within adult mental health teams found that formulation was used in many different ways, often unacknowledged, within