Recent publications within Contextual Behavioral Science provided a rationale for the expansion of intervention efficacy research using methods that capture idiographic factors and processes. We conducted a systematic review of the use and quality of single-case experimental designs (SCED) within the Acceptance and Commitment Therapy (ACT) literature in adult clinical populations. The systematic review was conducted according to PRISMA guidelines and the databases CINAHL, MEDLINE, PsycINFO, PsycArticles and OpenGrey were searched for peer-reviewed articles. Further studies were sought through review of reference lists of all full text studies. Studies were assessed against What Works Clearinghouse (WWC) single-case design standards. Twenty-six studies met eligibility criteria and were conducted within research teams all implementing multiple-baseline designs. Twenty-four studies did not meet WWC standards with most failing to ensure a degree of concurrence across participants. The extent of randomisation methods was also captured. The review highlights the sparsity of SCEDs within ACT literature in clinical populations and current methodological practices. Limitations of the review and implications for future research are discussed.

BACKGROUND: Hematopoietic cell transplantation (HCT) is a highly invasive and life-threatening treatment for hematological neoplasms and some types of cancer that can challenge the patient\'s meaning structures. Restoring meaning (i.e., building more flexible and significant explanations of the disease and treatment burden) can be aided by strengthening psychological flexibility by means of an Acceptance and Commitment Therapy (ACT) intervention. Thus, this trial aims to examine the effect of the ACT intervention on the meaning-making process and the underlying mechanisms of change in patients following HCT compared to a minimally enhanced usual care (mEUC) control group. The trial will be enhanced with a single-case experimental design (SCED), where ACT interventions will be compared between individuals with various pre-intervention intervals.
METHODS: In total, 192 patients who qualify for the first autologous or allogeneic HCT will be recruited for a two-armed parallel randomized controlled trial comparing an online self-help 14-day ACT training to education sessions (recommendations following HCT). In both conditions, participants will receive once a day a short survey and intervention proposal (about 5-10 min a day) in the outpatient period. Double-blinded assessment will be conducted at baseline, during the intervention, immediately, 1 month, and 3 months after the intervention. In addition, 6-9 participants will be invited to SCED and randomly assigned to pre-intervention measurement length (1-3 weeks) before completing ACT intervention, followed by 7-day observations at the 2nd and 3rd post-intervention measure. The primary outcome is meaning-related distress. Secondary outcomes include psychological flexibility, meaning-making coping, meanings made, and well-being as well as global and situational meaning.
CONCLUSIONS: This trial represents the first study that integrates the ACT and meaning-making frameworks to reduce meaning-related distress, stimulate the meaning-making process, and enhance the well-being of HCT recipients. Testing of an intervention to address existential concerns unique to patients undergoing HCT will be reinforced by a statistically rigorous idiographic approach to see what works for whom and when. Since access to interventions in the HCT population is limited, the web-based ACT self-help program could potentially fill this gap.
BACKGROUND: ClinicalTrials.gov ID: NCT06266182. Registered on February 20, 2024.

The use of single-case experimental design (SCED) to evaluate cognitive remediation is growing. SCEDs require rigorous methodology and appropriate choice of primary outcomes. To review primary outcomes that assess executive function impairments in patients with acquired brain injury (ABI). A scoping review was conducted using the Arksey and O\'Malley framework and the PRISMA extension for scoping review (PRISMA-ScR). Five databases were searched resulting in the inclusion of twenty-one studies. Primary outcomes were extracted and classified according to the type of measure, ecological setting and sources of possible bias. A wide variety of primary outcomes were identified; the majority of which evaluated behavioural performance during a real-life activity or in a real-life simulated setting. The most frequent bias observed across outcomes was the coaching effect. The findings of this scoping review highlight the importance of selecting appropriate outcomes for repeated measures in SCED studies. Direct observation of the target behaviour is a potential gold standard for assessing the effectiveness of a cognitive intervention.

Our objective is to implement a single-case experimental design (SCED) infrastructure in combination with experience-sampling methods (ESM) into the standard diagnostic procedure of a German outpatient research and training clinic. Building on the idea of routine outcome monitoring, the SCED infrastructure introduces intensive longitudinal data collection, individual effectiveness measures, and the opportunity for systematic manipulation to push personalization efforts further. It aims to empower psychotherapists and patients to evaluate their own treatment (idiographic perspective) and to enable researchers to analyze open questions of personalized psychotherapy (nomothetic perspective). Organized around the principles of agile research, we plan to develop, implement, and evaluate the SCED infrastructure in six successive studies with continuous stakeholder involvement: In the project development phase, the business model for the SCED infrastructure is developed that describes its vision in consideration of the context (Study 1). Also, the infrastructure\'s prototype is specified, encompassing the SCED procedure, ESM protocol, and ESM survey (Study 2 and 3). During the optimization phase, feasibility and acceptability are tested and the infrastructure is adapted accordingly (Study 4). The evaluation phase includes a pilot implementation study to assess implementation outcomes (Study 5), followed by actual implementation using a within-institution A-B design (Study 6). The sustainability phase involves continuous monitoring and improvement. We discuss to what extent the generated data could be used to address current questions of personalized psychotherapy research. Anticipated barriers and limitations during the implementation processes are outlined.

There are numerous effect measures researchers can select when conducting a meta-analysis of single-case experimental design research. These effect measures model different characteristics of the data, so it is possible that a researcher\'s choice of an effect measure could lead to different conclusions about the same intervention. The current study investigated the impact of effect measure selection on conclusions about the effectiveness of check-in check-out (CICO), a commonly used intervention within School-Wide Positive Behavior Interventions and Supports. Using a multilevel meta-analysis of seven different effect measures across 95 cases in 22 studies, findings suggested that all effect measures indicated statistically significant results of CICO in improving student behavior. However, the magnitude of the effects varied when comparing the results to interpretive guidelines, suggesting that the selection of effect measures may impact conclusions regarding the extent to which an intervention is effective. Implications, limitations, and future directions are discussed.

Count outcomes are frequently encountered in single-case experimental designs (SCEDs). Generalized linear mixed models (GLMMs) have shown promise in handling overdispersed count data. However, the presence of excessive zeros in the baseline phase of SCEDs introduces a more complex issue known as zero-inflation, often overlooked by researchers. This study aimed to deal with zero-inflated and overdispersed count data within a multiple-baseline design (MBD) in single-case studies. It examined the performance of various GLMMs (Poisson, negative binomial [NB], zero-inflated Poisson [ZIP], and zero-inflated negative binomial [ZINB] models) in estimating treatment effects and generating inferential statistics. Additionally, a real example was used to demonstrate the analysis of zero-inflated and overdispersed count data. The simulation results indicated that the ZINB model provided accurate estimates for treatment effects, while the other three models yielded biased estimates. The inferential statistics obtained from the ZINB model were reliable when the baseline rate was low. However, when the data were overdispersed but not zero-inflated, both the ZINB and ZIP models exhibited poor performance in accurately estimating treatment effects. These findings contribute to our understanding of using GLMMs to handle zero-inflated and overdispersed count data in SCEDs. The implications, limitations, and future research directions are also discussed.

People with primary psychosis are among the most seen in inpatient psychiatry. Treatment guidelines recommend both pharmacological and psychological treatments. However, psychological treatments are not routinely offered in many settings. There is also a lack of research on psychological treatments for this vulnerable population in the inpatient setting. The first aim of the current study was to examine treatment effects of a brief form of Acceptance and Commitment Therapy on outcomes valued by the treatment recipients. The second aim was to explore hypothetical processes of change in relation to outcomes over time. Three people with primary psychosis were treated for two to four sessions. A replicated single-case experimental design with multiple baselines across subjects (Clinical Trials registration number ID NCT04704973) was employed to examine treatment effects. The Personal Questionnaire (PQ) was used as primary outcome, symptom believability and preoccupation as proposed processes of change. Data were analyzed using visual inspection, calculation of Tau-U values, and cross-lagged correlation. All participants improved significantly on PQ and the symptom preoccupation measure. Two improved significantly on the symptom believability measure. Cross-lagged correlation analyses showed no clear mediation. Change in proposed processes of change and primary outcome predominantly happened concomitantly, although patterns of results reflected individual differences.

Meta-analysis is of increasing importance as this quantitative synthesis technique has the potential to summarize a tremendous amount of research evidence, which can help making evidence-based decisions in policy, practice, and theory. This paper examines the single-case meta-analyses within the Education and Psychology fields. The amount of methodological studies related to the meta-analysis of Single-Case Experimental Designs (SCEDs) is increasing rapidly, especially in these fields. This underscores the necessity of a succinct summary to help methodologists identify areas for further development in Education and Psychology research. It also aids applied researchers and research synthesists in discerning when to use meta-analytic techniques for SCED studies based on criteria such as bias, mean squared error, 95% confidence intervals, Type I error rates, and statistical power. Based on the summary of empirical evidence from 18 reports identified through a systematic search procedure, information related to meta-analytic techniques, data generation and analysis models, design conditions, statistical properties, conditions under which the meta-analytic technique is appropriate, and the study purpose(s) were extracted. The results indicate that three-level hierarchical linear modeling is the most empirically validated SCED meta-analytic technique, and parameter bias is the most prominent statistical property investigated. A large number of primary studies (more than 30) and at least 20 measurement occasions per participant are recommended for usage of SCED meta-analysis in Education and Psychology fields.

OBJECTIVE: Essential vocal tremor (EVT) manifests as nearly rhythmic modulations of fundamental frequency (fo) and intensity and causes a shaky voice. Although research on behavioral therapy for EVT is limited, previous studies have shown that a breathy voice reduces the perception of simulated EVT and might be an effective compensatory strategy. The current study aimed to measure the acoustical and perceptual effects of a breathy voice strategy in speakers with EVT.
METHODS: A single-case experimental design (SCED) was used to investigate acoustical effects, and a pair comparison listening task was used to investigate perceptual effects.
METHODS: Three participants with EVT matched five different levels of breathiness produced by a computational model. Acoustical analyses of the rate and extent of fo and intensity modulation were performed to estimate EVT severity for baseline and treatment trials. Statistical analyses were completed using Tau-U. Twenty novice listeners participated in the perceptual study to determine if treatment trials sounded less \"shaky\" than baseline trials. Statistical analyses were completed using one sample t tests.
RESULTS: The acoustical effects were variable across different levels of breathiness for all three participants. All participants were able to adjust their levels of breathiness based on auditory models and verbal cues but did not achieve the target levels of breathiness. Listeners did not perceive the breathy trials to be less \"shaky\" than baseline trials for any level of breathiness.
CONCLUSIONS: The breathy voice strategy had variable effects on the acoustical measures of EVT, supporting the use of a single-case experimental design to investigate the effectiveness of behavioral treatment for EVT. Listeners perceived breathy trials to be \"shakier\" than baseline trials, which was inconsistent with our hypothesis and previous studies of EVT. Future research should evaluate the use of a breathy voice in speakers with confirmed laryngeal tremor, optimize cueing for breathiness, and provide more opportunities to practice the breathy strategy.

BACKGROUND: Health anxiety (HA) by proxy is described as parents\' obsessive worries that their child is severely ill although this is not medically confirmed. Research on HA by proxy suggests that it is highly distressing for the parent and that the child may be at risk of developing maladaptive symptom coping strategies. No targeted treatment for this group exists. We developed PROXY, an 8-week psychological internet-delivered treatment for parents with HA by proxy. The treatment components of PROXY are informed by cognitive behavioral therapy as well as acceptance and commitment therapy, and it was developed in collaboration with parents experiencing HA by proxy and clinical experts.
OBJECTIVE: This paper describes the protocol for a study investigating the potential effects of PROXY on parents\' worries about their children\'s health using a single-case experimental design (SCED).
METHODS: Five parents clinically evaluated as experiencing HA by proxy will be included. A replicated randomized SCED study will be conducted in which each participant will be randomized to receive treatment after a baseline period of between 7 and 26 days (phase A). The treatment phase duration is 8 weeks for all participants (phase B), followed by a follow-up phase lasting between 14 and 33 days (phase C), ensuring that all participants remain in the study for 96 days. Participants will report daily anxiety level by SMS text message throughout the study. They will also answer self-report questionnaires, including questions on HA by proxy and own HA, 4 times during the study. Data will be submitted to structured visual analysis to inspect anxiety level, the variability of anxiety, trends, the overlap of data points among phases, when effects occur, and the consistency of data patterns across participants. Furthermore, randomization tests will be conducted for each participant to test the null hypothesis that PROXY will have no effect on participants\' anxiety.
RESULTS: The recruitment of parents began in June 2022. As of March 2, 2023, a total of 4 parents have been included in the study. Data collection was expected to cease in April 2023.
CONCLUSIONS: To the best of our knowledge, this protocol describes the only study of treatment for HA by proxy. As the prevalence of this condition is still unknown, a SCED was chosen because this method allows the inclusion of very few participants while still providing information on effects and treatment courses. Conducting the study with a replicated randomized phase design enables methodologically sound testing despite the inclusion of very few participants. The results will inform researchers on individual treatment courses and effects, which may direct future research in terms of the possible mechanisms of change, ideas for how to refine the treatment content, and how the treatment may be offered to patients in the future.
BACKGROUND: ClinicalTrials.gov NCT04830605; https://clinicaltrials.gov/study/NCT04830605.
UNASSIGNED: DERR1-10.2196/46927.