Blog: Moving towards a better understanding of idiographic outcome measurement

by Jenna Jacob, CORC Research Lead

I was invited to write a commentary to go alongside a systematic review of idiographic measures used in psychotherapy settings, by Lloyd, Duncan and Cooper (2019). My brief was to focus on one or more issues in the area and within that context discuss the paper. I chose to focus on the promotion of goal-based outcome measures as a way to track individualised outcomes alongside other types of measure and to discuss the inclusion of the goal-based outcomes tool (GBO; Law, 2011) in the NHS Mental Health Services Data Set (MHSDS) outcome metric.

In the paper, I discuss some of the benefits and challenges of all types of outcome measurement. I suggest how different types of measures might be used alongside each other for different purposes. For example, to date, standardised measures (where there is a fixed set of items, often relating to symptomology) have often been used to evidence change on an aggregate level. However, research on goal-based outcome measures has found that there is only evidence of them being used on an individual level. This is primarily because fairly little is known about how goal-based outcome measures work psychometrically and because they have been traditionally introduced and used as clinical tools first and foremost.

In the paper, I introduce the provisionally termed “combined change” metric, which brings together reliable change analysis of standardised and goal-based outcome measures for the first time. The Reliable Change Index is the nationally agreed way forward for reporting on the data derived from the standardised outcome measures (RCI; Jacobson & Truax., 1991). This calculation takes into consideration measurement error and so change shown in scores is likely to be explained by more than just the imprecision of the measures. The goal-based reliable change analysis is based on previous research we did on the GBO data in the CORC dataset (Edbrooke-Childs et al., 2015). This is a new metric being trialled by NHS England in the MHSDS from this year. The careful use of both standardised and idiographic (e.g. goal-based outcome measures) continues to be encouraged.

The systematic review produced by Lloyd et al. (2019) fills a research gap whereby there was previously no up to date overview of goal-based outcome measures which have been used in therapeutic settings. Their research is useful to clinicians and researchers alike, as it summarises which goal-based outcome measures have been used, alongside the published psychometric properties. Therefore, clinicians are now able to make more informed decisions about the choice of goal-based outcome measure to use. This review provides a useful platform from which to grow the evidence base and helps us to move towards a better understanding of goal-based outcome measures.

Useful resources


Edbrooke-Childs, J., Jacob, J., Law, D., Deighton, J., & Wolpert, M. (2015). Interpreting standardized and idiographic outcome measures in CAMHS: what does change mean and how does it relate to functioning and experience? Child and Adolescent Mental Health, 20(3), 142-148.

Jacob, J. Moving toward a better understanding of idiographic outcome measurement: A commentary on Lloyd, Duncan, and Cooper (2019). Clinical Psychology: Science and Practice, e12287.

Jacobson, N. S., & Truax, P. (1991). Clinical significance: a statistical approach to defining meaningful change in psychotherapy research. Journal of consulting and clinical psychology, 59(1), 12-19.

Law, D. (2011). Goals and Goal Based Outcomes (GBOs): Some Useful Information. Version 2.0.

Lloyd, C. E. M., Duncan, C., & Cooper, M. (2019). Goal measures for psychotherapy: A systematic review of self-report, idiographic instruments. Clinical Psychology: Science and Practice. e12281

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