The influence of procedural characteristics on within-case effect sizes for academic outcomes.

Single-case experimental designs (SCEDs) have been used with increasing frequency to identify evidence-based interventions in education. The purpose of this study was to explore how several procedural characteristics, including within-phase variability (i.e., measurement error), number of baseline observations, and number of intervention observations influenced the magnitude of four SCED effect sizes, including (a) non-overlap of all pairs (NAP), (b) baseline corrected tau (BC-Tau), (c) mean-phase difference (MPD), and (d) generalized least squares (GLS) when applied to hypothetical academic intervention SCED data. Higher levels of measurement error decreased the average magnitude of effect sizes, particularly NAP and BC-Tau. However, the number of intervention observations had minimal impact on the average magnitude of NAP and BC-Tau. Increasing the number of intervention observations dramatically increased the magnitude of GLS and MPD. Increasing the number of baseline observations also tended to increase the average magnitude of MPD. The ratio of baseline to intervention observations had a statistically but not practically significant influence on the average magnitude of NAP, BC-Tau, and GLS. Careful consideration is required when determining the length of time academic SCEDs are conducted and what effect sizes are used to summarize treatment outcomes. This article also highlights the value of using meaningful simulation conditions to understand the performance of SCED effect sizes.

Extensions of open science for applied behavior analysis: Preregistration for single-case experimental designs.

Open science practices are designed to enhance the utility, integrity, and credibility of scientific research. This article highlights how preregistration in open science practice can be leveraged to enhance the rigor and transparency of single-case experimental designs within an applied behavior analysis framework. We provide an overview of the benefits of preregistration including increased transparency, reduced risk of researcher bias, and improved replicability, and we review the specific contexts under which these practices most benefit the proposed framework. We discuss potential concerns with and unique considerations for preregistering experiments that use single-case designs, with practical guidance for researchers who are seeking to preregister their studies. We present a checklist as a tool for researchers in applied behavior analysis to use for preregistration and provide recommendations for our field to strengthen the contingencies for open science practices that include preregistration.

Unlocking the benefits of montessori-based reading activities in nursing home: A multiple baseline study on groups of individuals with severe dementia.

OBJECTIVE: Group activities are commonly offered to residents of nursing homes, and increasingly with a person-centred care approach. The aim of this study is to compare the impacts of a Montessori-based reading activity with a more traditional reading activity. METHOD: A multiple baseline design was used, with 3 groups of 5 older adults with moderate to severe dementia. All sessions were videorecorded and analysed by independent judges, blinded to our hypotheses and conditions. Impacts of the type of activity (storytelling or Montessori-based reading) on verbal interactions, engagement level, affect and behavioural aspects were estimated with both visual analyses and statistical analyses using the between-case standardised mean differences method. RESULTS: Significant differences were found in favour of the Montessori-based activities with regard to the number of verbal interactions, constructive and passive engagement and positive affect expressed, with moderate to large effect size (from 0.46 to 1.66). CONCLUSION: The Montessori-based reading group activity really seems to be preferable to a more traditional storytelling activity, with multiple benefits for residents. Depending on the preserved abilities and interests of the participants, it can also be aimed at people with severe dementia.

Model selection of GLMMs in the analysis of count data in single-case studies: A Monte Carlo simulation.

Generalized linear mixed models (GLMMs) have great potential to deal with count data in single-case experimental designs (SCEDs). However, applied researchers have faced challenges in making various statistical decisions when using such advanced statistical techniques in their own research. This study focused on a critical issue by investigating the selection of an appropriate distribution to handle different types of count data in SCEDs due to overdispersion and/or zero-inflation. To achieve this, I proposed two model selection frameworks, one based on calculating information criteria (AIC and BIC) and another based on utilizing a multistage-model selection procedure. Four data scenarios were simulated including Poisson, negative binominal (NB), zero-inflated Poisson (ZIP), and zero-inflated negative binomial (ZINB). The same set of models (i.e., Poisson, NB, ZIP, and ZINB) were fitted for each scenario. In the simulation, I evaluated 10 model selection strategies within the two frameworks by assessing the model selection bias and its consequences on the accuracy of the treatment effect estimates and inferential statistics. Based on the simulation results and previous work, I provide recommendations regarding which model selection methods should be adopted in different scenarios. The implications, limitations, and future research directions are also discussed.

A Quantitative Systematic Literature Review of Combination Punishment Literature: Progress Over the Last Decade.

This review evaluated single-case experimental design research that examined challenging behavior interventions utilizing punishment elements. Thirty articles published between 2013 and 2022 met study inclusion criteria. Study quality was also assessed. Through multiple levels of analysis (e.g., descriptive statistics, non-parametric statistics), we examined (a) participant and study trends, (b) differential outcomes related to temporal reinforcement approaches (antecedent, consequent, or combined reinforcement) applied alongside punishment element(s), (c) differential outcomes related to the punishment type (negative, positive) applied alongside reinforcement, and (d) effect sizes associated with study rigor across peer-reviewed and gray literature. Our results may tentatively suggest that, for certain situations, concurrently applying punishment with antecedent reinforcement approaches may coincide with significantly larger effect sizes compared to combined temporal reinforcement approaches, while positive punishment applied concurrently with reinforcement may coincide with larger but non-significant intervention effects. Most featured articles met rigor criteria, but larger effects were seen in peer-reviewed literature.

Neuromuscular electrical stimulation to combat cognitive aging in people with spinal cord injury: protocol for a single case experimental design study.

INTRODUCTION: Individuals with spinal cord injury (SCI) can experience accelerated cognitive aging. Myokines (factors released from muscle cells during contractions), such as brain-derived neurotrophic factor (BDNF), are thought to have beneficial effects on cognition. Neuromuscular electrical stimulation (NMES) was shown to elicit a large release of myokines. However, the effects of NMES on cognitive function have not been studied. OBJECTIVE: To present the study protocol for a clinical trial evaluating the effects of NMES aimed at improving cognition and BDNF. METHODS: A replicated randomized three-phases single-case experimental design (SCED) with sequential multiple baseline time series and a single-armed prospective trial will be conducted with 15 adults with chronic SCI (> 12 months after injury) above L1 neurological level undergoing 30-min quadriceps NMES, 3 days per week for 12 weeks. MAIN STUDY ENDPOINTS: Primary endpoint is cognitive performance (assessed by a smartphone test) conducted three times per week during the baseline phase with random duration of 3 to 8 weeks, the intervention phase of 12 weeks, and the follow-up phase of 3 weeks after a no measurement rest period of 12 weeks. Secondary endpoints are changes in BDNF levels and cognitive performance measured before the baseline period, before and after intervention and after a 12 weeks follow-up. CONCLUSION: This will be the first study investigating the effects of 12 weeks NMES on both cognition and BDNF levels in individuals with SCI. The SCED results provide information on individual treatment effect courses which may direct future research. TRIAL REGISTRATION: ClinicalTrials.gov (NCT05822297, 12/01/2023).

The effect of an online acceptance and commitment intervention on the meaning-making process in cancer patients following hematopoietic cell transplantation: study protocol for a randomized controlled trial enhanced with single-case experimental design.

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. DISCUSSION: 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. TRIAL REGISTRATION: ClinicalTrials.gov ID: NCT06266182. Registered on February 20, 2024.

A Systematic Quality Review of Single-Case Experimental Designs Using Acceptance and Commitment Therapy in Adult Clinical Populations.

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.

Assessment of executive function impairments in adults with acquired brain injury across single-case experimental design: A scoping review of primary outcomes.

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.

Aphasia, depression, and psychological therapy (ADaPT): A single case design evaluation of a modified cognitive behavioural therapy to treat depressive symptoms in stroke survivors with aphasia.

Cognitive behavioural therapy (CBT) can effectively treat depression in the general population, but there is a lack of studies evaluating CBT tailored to specific cognitive and communication needs of individuals with post-stroke aphasia. We aimed to evaluate the feasibility and preliminary efficacy of a modified CBT intervention to ameliorate depressive symptoms. An ABA withdrawal/reversal single case design with concurrent multiple baselines (2.5, 4.5, or 6.5 weeks) was repeated across 10 participants (six male, four female) with post-stroke aphasia and self-reported depression. Participants completed 10 individual intervention sessions with a clinical neuropsychologist and a 4-week follow-up. The primary outcome was self-rated depression, and secondary outcomes included observer-rated symptoms of depression and anxiety. Data were analysed visually and statistically controlling for baseline trend. Feasibility was addressed by analysing recruitment and retention rates, treatment adaptations, and fidelity ratings. Three participants self-reported decreased depression levels during the intervention phase, which was sustained for two participants. Four additional participants improved during the follow-up phase. Close others reported sustained improvements in depressive symptoms (six participants) and anxiety symptoms (seven participants). Modified CBT appears feasible and potentially efficacious in reducing depressive symptoms in post-stroke aphasia. A randomized controlled trial is warranted, and should consider additional treatment sessions.

Grammar intervention using graduated input type variation (GITV) for pre-primary children: A single-case experimental design study.

PURPOSE: This study examined the early efficacy of a new theory-driven principle of grammar intervention, graduated input type variation (GITV). METHOD: Three Cantonese-speaking children, aged between 4;01 and 5;10, with oral language difficulties participated in this single baseline within-participant single case experimental study. The children received a total of 300 teaching episodes of the target serial verb construction via focused stimulation and recast over 10 30- to 45-minute sessions. The 30 exemplars of the target included low type variation of the verbs in each of the first five sessions, followed by high type variation in the remaining sessions. RESULT: Visual analysis revealed that all children improved their performance in the target construction but not the control vocabulary in the probes, suggesting a treatment effect. Maintenance of treatment effects was also observed in all children. Positive results in across-behaviour generalisation to the untrained construction were observed in all children. Generalisation to other less structured linguistic contexts and to the narrative retell discourse context was minimal and observed in one child only. CONCLUSION: Preliminary evidence suggested early efficacy of GITV as a principle for grammar intervention. Modifications in the research methodology are recommended for future studies involving children with developmental language disorder.

Leveraging Single-Case Experimental Designs to Promote Personalized Psychological Treatment: Step-by-Step Implementation Protocol with Stakeholder Involvement of an Outpatient Clinic for Personalized Psychotherapy.

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.

A Comparison of Single-Case Effect Measures Using Check-In Check-Out Data.

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.

The effect of eye movement desensitization and reprocessing on fibromyalgia: A multiple-baseline experimental case study across ten participants.

Fibromyalgia (FM) is a chronic pain disorder characterized by widespread musculoskeletal pain, fatigue, and stiffness in muscles and joints. Traumatic life experiences and post-traumatic stress symptoms play a role in its development and persistence. Although previous research suggests that pain and FM symptoms decrease after eye movement desensitization and reprocessing (EMDR) therapy, its effectiveness has not been investigated in a controlled manner. The present study investigated the effectiveness of a six-session, 90-minute EMDR therapy using a multiple baseline single-case experimental design (SCED) across ten adult females with FM. The SCED involved a baseline, intervention, one- and three-month follow-up phase. The primary outcome was pain. Secondary outcomes included post-traumatic stress symptoms, other FM symptoms (fatigue, stiffness in muscles and joints), and the impact of FM on daily activities and sleep. Data were statistically analyzed by primarily testing means across phases on an individual and group level. Post-traumatic stress symptoms improved significantly in seven participants. Pain severity decreased significantly in six participants, with three of them maintaining significant improvement three months later. One participant showed clinically relevant change one month later. Furthermore, improvements were observed in secondary outcome measures. The findings support the efficacy of EMDR in reducing FM symptoms.

Multilevel modeling in single-case studies with zero-inflated and overdispersed count data.

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.

Ultra-brief acceptance & commitment therapy for inpatients with psychosis - a single-case experimental design investigating processes of change.

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.

A single case experimental design study using an operationalised version of the Kaufman Speech to Language Protocol for children with childhood apraxia of speech.

PURPOSE: A Phase I study was conducted to examine the treatment effectiveness of the Kaufman Speech to Language Protocol using a research-operationalised protocol. It was hypothesised that articulatory accuracy would improve as a result of the treatment and that these improvements would be maintained after treatment was discontinued. METHOD: A single case experimental design was used to evaluate the effectiveness of the Kaufman Speech to Language Protocol. Four children with a confirmed childhood apraxia of speech diagnosis were included in this study. Each child received 12 individual 1 hr treatment sessions that each consisted of an approximation setting phase and a practice phase. Probe data was collected during treatment and at post-treatment time points to measure treatment effectiveness and to measure changes in the untreated words. Untreated (control) sounds were included to test whether recorded improvements in articulatory accuracy could be attributed to the Kaufman Speech to Language Protocol. RESULT: Two of the four children demonstrated a response to the intervention and maintenance of these changes, while the two remaining children demonstrated some generalisation in the absence of improved target (treatment) words. No specific child factors were clearly associated with positive treatment outcomes. CONCLUSION: This study replicated the findings of an earlier pilot study and found that the operationalised protocol for the Kaufman Speech to Language Protocol is effective in improving articulatory accuracy for some children with childhood apraxia of speech. Additional replication with a further refined treatment protocol and a larger sample size is needed to support a recommendation of clinical use of the Kaufman Speech to Language Protocol.

How to assess and take into account trend in single-case experimental design data.

One of the data features that are expected to be assessed when analyzing single-case experimental designs (SCED) data is trend. The current text deals with four different questions that applied researchers can ask themselves when assessing trend and especially when dealing with improving baseline trend: (a) What options exist for assessing the presence of trend?; (b) Once assessed, what criterion can be followed for deciding whether it is necessary to control for baseline trend?; (c) What strategy can be followed for controlling for baseline trend?; and (d) How to proceed in case there is baseline trend only in some A-B comparisons? Several options are reviewed for each of these questions in the context of real data, and tentative recommendations are provided. A new user-friendly website is developed to implement the options for fitting a trend line and a criterion for selecting a specific technique for that purpose. Trend-related and more general data analytical recommendations are provided for applied researchers.Trial registration: ClinicalTrials.gov identifier: NCT04560777.

Benefits of a targeted rehabilitation of number transcoding in secondary acalculia: A single-case experimental design.

BACKGROUND: Despite its potentially significant functional and emotional impact, acalculia is still too rarely assessed and managed by speech and language therapists. Research on the rehabilitation of numerical transcoding remains scarce in the literature and, despite positive results, presents a low level of evidence. AIMS: The present study aims to evaluate the effectiveness of a targeted rehabilitation of numerical transcoding in two patients suffering from a chronic secondary acalculia. METHODS & PROCEDURES: Two post-brain injury females with secondary acalculia took part in a single-case experimental design with multiple baseline across subjects according to a three-phase experimental protocol: baseline involving global cognitive rehabilitation (5-7 measurements with randomized sequential introduction); targeted intervention (10 measurements); follow-up (2 immediate measurements and 1 month after the end of the intervention). Repeated outcome measures consisted of six lists composed of numbers of equivalent difficulty that were used alternately to assess numerical transcoding. We used a reverse digit span as a control measure to assess the specificity of the intervention. Rehabilitation lasted 5 weeks and consisted of errorless learning with colour cues, tables and number-words cards. OUTCOMES & RESULTS: During baseline period involving global cognitive rehabilitation, transcoding scores remained unchanged. In contrast, there was a significant improvement in scores for both patients during the intervention phase targeting transcoding and maintenance of benefits 1-month post-intervention. CONCLUSIONS & IMPLICATIONS: This study demonstrates that a specific rehabilitation targeting numerical transcoding following chronic secondary acalculia can be effective in improving transcoding skills. WHAT THIS PAPER ADDS: What is already known on the subject Transcoding difficulties in patients with acalculia can cause a significant disability in everyday life activities. In secondary acalculia, rehabilitation of cognitive functions associated with number processing (attention, working memory, language) is not sufficient for improvement of transcoding. What this paper adds to existing knowledge An intervention specifically targeting numerical transcoding significantly and durably improves the skills of patients with chronic secondary acalculia. What are the potential or actual clinical implications of this work? Procedural error-free intervention using colour cueing, tables, cards with number-words, copy and repetition seems effective to improve transcoding skills in chronic acalculia.

Internet-Delivered Therapy for Parents With Health Anxiety by Proxy: Protocol for a Single-Case Experimental Design Study.

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. TRIAL REGISTRATION: ClinicalTrials.gov NCT04830605; https://clinicaltrials.gov/study/NCT04830605. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/46927.