Jaap Lancee’ (Clinical Psychology) question:
Dear Marija,
A couple of years ago we published a case series together on the effects of sleep treatment on depression. I must admit this was the first case series I did but I thought it provided very interesting data. I really liked your enthusiasm about the single-case experimental designs. Could you explain why these designs are so helpful in investigating treatment effects? Additionally could you explain what the newest developments in this area are?
Jaap
Marija Maric’s (Developmental Psychopathology) answer:
Dear Jaap,
Thank you for your interest and this important query! Single-Case Experimental Designs (SCEDs) are within-individual comparisons increasingly recognized as a valuable alternative for Randomized Controlled Trials (RCTs) to test intervention effects in youth and adult populations. In SCEDs, the symptoms of interest of one or several participants are tested regularly, for example, weekly, daily, or hourly, over different phases of the study (e.g., baseline period followed by treatment period). Multiple advantages of SCEDs are identified. In clients with heterogeneous problems or clients with a specific comorbidity, SCEDs may be the only way to investigate treatment effects, either because collecting large-group data would not be feasible within the timeframe of the study or because analyses on a group level would imply loss of important information (i.e., finding no intervention effect while an effect is present in a certain subgroup). Further, SCEDs can be used to test (novel) interventions prior to investigations in potentially demanding and costly RCTs. SCEDs also offer a great opportunity to stimulate collaboration between research and practice, unifying research questions that emerge from clinical practice on the one hand, and, on the other hand, research methodology to test these questions on the level of a single client.
But – perhaps the largest contribution of SCEDs is that now we can test intervention effects on the level of a single person. RCT methods depart from the variable-oriented approaches, deliver information about average treatment effects in a group, and thus assume that intervention effects are homogeneous within a certain population. However, conclusions about changes in psychological symptoms made at population level often do not generalize to a single person. The newest developments in the area of SCEDs are definitely ones related to statistical data-analysis techniques. Within one research study one or multiple SCEDs can be included and analyzed, and individual SCEDs can nowadays even be meta-analyzed, increasing the generalizability of this type of research. We have recently conducted the (so far known) first meta-analysis of single-case studies in the area of treatment of psychological problems (Maric and colleagues, in revision).
Marija
Marija Maric’s question is for Bianca Boyer (Developmental Psychology):
Dear Bianca,
We share the same passion for the conduct of youth intervention research. Can you tell us what the newest developments are in this area and why is it now – more than ever – the right moment to pay extensive attention to research and clinical practice in youth mental health?
Marija
References
– Maric, M., Schumacher, L., Van Den Noortgate, W., Bettelli, L., Engelbertink, W., & Stikkelbroek, Y. (in revision). Within-person effects in the treatment of internalizing disorders in youth: A multilevel meta-analysis of Single Case (Experimental) Design studies.
Jaap Lancee’ (Clinical Psychology) question:
Dear Marija,
A couple of years ago we published a case series together on the effects of sleep treatment on depression. I must admit this was the first case series I did but I thought it provided very interesting data. I really liked your enthusiasm about the single-case experimental designs. Could you explain why these designs are so helpful in investigating treatment effects? Additionally could you explain what the newest developments in this area are?
Jaap
Marija Maric’s (Developmental Psychopathology) answer:
Dear Jaap,
Thank you for your interest and this important query! Single-Case Experimental Designs (SCEDs) are within-individual comparisons increasingly recognized as a valuable alternative for Randomized Controlled Trials (RCTs) to test intervention effects in youth and adult populations. In SCEDs, the symptoms of interest of one or several participants are tested regularly, for example, weekly, daily, or hourly, over different phases of the study (e.g., baseline period followed by treatment period). Multiple advantages of SCEDs are identified. In clients with heterogeneous problems or clients with a specific comorbidity, SCEDs may be the only way to investigate treatment effects, either because collecting large-group data would not be feasible within the timeframe of the study or because analyses on a group level would imply loss of important information (i.e., finding no intervention effect while an effect is present in a certain subgroup). Further, SCEDs can be used to test (novel) interventions prior to investigations in potentially demanding and costly RCTs. SCEDs also offer a great opportunity to stimulate collaboration between research and practice, unifying research questions that emerge from clinical practice on the one hand, and, on the other hand, research methodology to test these questions on the level of a single client.
But – perhaps the largest contribution of SCEDs is that now we can test intervention effects on the level of a single person. RCT methods depart from the variable-oriented approaches, deliver information about average treatment effects in a group, and thus assume that intervention effects are homogeneous within a certain population. However, conclusions about changes in psychological symptoms made at population level often do not generalize to a single person. The newest developments in the area of SCEDs are definitely ones related to statistical data-analysis techniques. Within one research study one or multiple SCEDs can be included and analyzed, and individual SCEDs can nowadays even be meta-analyzed, increasing the generalizability of this type of research. We have recently conducted the (so far known) first meta-analysis of single-case studies in the area of treatment of psychological problems (Maric and colleagues, in revision).
Marija
Marija Maric’s question is for Bianca Boyer (Developmental Psychology):
Dear Bianca,
We share the same passion for the conduct of youth intervention research. Can you tell us what the newest developments are in this area and why is it now – more than ever – the right moment to pay extensive attention to research and clinical practice in youth mental health?
Marija
