Single-subject Studies Research Articles

Social Story Intervention for Training Expected Behaviors among Preschool Children: A Systematic Review and Meta-Analysis.

Promoting appropriate behaviors in early childhood is crucial for children's future development. This systematic review aimed to explore the efficacy of social story (SS) intervention in teaching expected behaviors among preschool children. A structured search strategy was applied to five online electronic databases. The references were systematically screened in accordance with the PRISMA statements. Randomized or non-randomized controlled studies, as well as single-subject studies, in which SSs served as a behavioral training approach for children aged 2 to 6 years were included. Information related to study design, characteristics of the participants, target behaviors, and implementation of SS intervention was extracted. A meta-analysis was performed using the random-effects model, where similar outcomes were evaluated by similar intervention across multiple studies. Twenty-one studies were identified for qualitative analysis, while two studies formed the basis of the meta-analysis. SS interventions were employed to teach a variety of behaviors among typically developing children as well as those with various disabilities, such as autism, developmental delay, hearing impairments, attention deficit hyperactivity disorder, or other disabilities. The target behaviors included oral health practices, peer interaction, staying on-task, self-regulation, sleep habits, and controlling aggressive behavior during group activities. The SSs were used either alone or combined with other strategies, such as positive reinforcement, music therapy, role play, group discussion, video self-modeling, immediate practices, or additional audio commentary. Most studies reported improvements in appropriate behaviors and/or reductions in unfavorable behaviors. The meta-analysis indicated that children practiced more toothbrushing steps when using SS interventions compared to conventional oral health instruction (Z = 3.60, MD = 0.66, 95%CI 0.30 to 1.02, p < 0.001). SS interventions have the potential to teach target behaviors, particularly toothbrushing behaviors, among preschool children. More well-designed randomized controlled trials are warranted to determine the efficacy of SS interventions among children with various developmental profiles.

Through their eyes: Multi-subject brain decoding with simple alignment techniques

Abstract To-date, brain decoding literature has focused on single-subject studies, that is, reconstructing stimuli presented to a subject under fMRI acquisition from the fMRI activity of the same subject. The objective of this study is to introduce a generalization technique that enables the decoding of a subject’s brain based on fMRI activity of another subject, that is, cross-subject brain decoding. To this end, we also explore cross-subject data alignment techniques. Data alignment is the attempt to register different subjects in a common anatomical or functional space for further and more general analysis. We utilized the Natural Scenes Dataset, a comprehensive 7T fMRI experiment focused on vision of natural images. The dataset contains fMRI data from multiple subjects exposed to 9,841 images, where 982 images have been viewed by all subjects. Our method involved training a decoding model on one subject’s data, aligning new data from other subjects to this space, and testing the decoding on the second subject based on information aligned to the first subject. We also compared different techniques for fMRI data alignment, specifically ridge regression, hyper alignment, and anatomical alignment. We found that cross-subject brain decoding is possible, even with a small subset of the dataset, specifically, using the common data, which are around 10% of the total data, namely 982 images, with performances in decoding comparable to the ones achieved by single-subject decoding. Cross-subject decoding is still feasible using half or a quarter of this number of images with slightly lower performances. Ridge regression emerged as the best method for functional alignment in fine-grained information decoding, outperforming all other techniques. By aligning multiple subjects, we achieved high-quality brain decoding and a potential reduction in scan time by 90%. This substantial decrease in scan time could open up unprecedented opportunities for more efficient experiment execution and further advancements in the field, which commonly requires prohibitive (20 hours) scan time per subject.

Evaluating Covert Sensitization in the Treatment of Male Sex Addicts: Three Single Subject Studies

Evaluating Covert Sensitization in the Treatment of Male Sex Addicts: Three Single Subject Studies

The dynamics of social activation and suspiciousness in individuals at ultra-high risk for psychosis

IntroductionSocial functioning is often impaired during the ultra-high risk (UHR) phase for psychosis, but group-level studies regarding the role of social functioning in transition to psychosis are inconsistent. Exploring the inter-individual differences which underlie the association between social functioning and psychotic symptoms in this phase could yield new insights. ObjectiveTo examine the idiographic and dynamic association between social activation and suspiciousness in individuals at UHR for psychosis using time-series analysis. MethodsTwenty individuals at UHR for psychosis completed a diary application every evening for 90 days. Two items on social activation (quantity: ‘time spent alone’ and quality: ‘feeling supported’) and two items on suspiciousness (‘feeling suspicious’ and ‘feeling disliked’) were used. Time series (T = 90) of each individual were analyzed using vector auto regression analysis (VAR), to estimate the lagged (over 1 day) effect of social activation on suspiciousness, and vice versa, as well as their contemporaneous associations. ResultsHeterogeneous person-specific associations between social activation and suspiciousness were found in terms of strength, direction and temporal aspects. ConclusionsThe association between social activation and suspiciousness differs amongst individuals who are at UHR for psychosis. These findings underline the importance of tailoring psychosocial interventions to the individual. Future studies may examine whether using results of single-subject studies in clinical practice to personalize treatment goals leads to better treatment outcomes.

A practical model-based segmentation approach for improved activation detection in single-subject functional magnetic resonance imaging studies.

Functional magnetic resonance imaging (fMRI) maps cerebral activation in response to stimuli but this activation is often difficult to detect, especially in low-signal contexts and single-subject studies. Accurate activation detection can be guided by the fact that very few voxels are, in reality, truly activated and that these voxels are spatially localized, but it is challenging to incorporate both these facts. We address these twin challenges to single-subject and low-signal fMRI by developing a computationally feasible and methodologically sound model-based approach, implemented in the R package MixfMRI, that bounds the a priori expected proportion of activated voxels while also incorporating spatial context. An added benefit of our methodology is the ability to distinguish voxels and regions having different intensities of activation. Our suggested approach is evaluated in realistic two- and three-dimensional simulation experiments as well as on multiple real-world datasets. Finally, the value of our suggested approach in low-signal and single-subject fMRI studies is illustrated on a sports imagination experiment that is often used to detect awareness and improve treatment in patients in persistent vegetative state (PVS). Our ability to reliably distinguish activation in this experiment potentially opens the door to the adoption of fMRI as a clinical tool for the improved treatment and therapy of PVS survivors and other patients.

A Systematic Review of the Use of Acceptance and Commitment Therapy to Treat Adult Obsessive-Compulsive Disorder

The present review aims to critically evaluate available literature on the use of acceptance and commitment therapy (ACT) to treat adult obsessive-compulsive disorder (OCD) and to draw conclusions about using ACT to reduce OCD symptoms in adults with OCD. Databases (PsycINFO, PsycARTICLES, MEDLINE, and PubMed), Google Scholar, and article references were used to identify relevant studies through October 10, 2020. This review includes both peer-reviewed, published articles (n = 15) and unpublished theses and dissertations (n = 2) to increase the breadth of the review as suggested by PRISMA guidelines. Reviewed articles utilized ACT and at least one measure of OCD symptom severity. Information on methodological, measurement, statistical, and analytical characteristics of the included studies were extracted to determine the quality of the available studies and to inform the conclusions of this review. Seventeen studies (n = 17) with 336 participants from three countries were evaluated. The current evidence suggests that ACT can be used to reduce symptoms of OCD in adults. A conclusion supporting the use of ACT to reduce OCD symptoms can be made because of several strengths within this body of literature (e.g., use of validated OCD symptom measures, inclusion of treatment manuals, use of multiple assessment points, etc.). However, because a majority of the included studies are quasi-experimental and single-subject studies, more stringent research (i.e., randomized controlled trials) with large, diverse samples is needed to strengthen this conclusion. Additionally, dismantling studies exploring the components of ACT that lead to OCD symptom improvement are needed.

초등학교 ADHD아동을 위한 중재적 개입 국내 연구 동향 및 질적 지표 분석

Objectives Domestic studies related to intervention programs for children with ADHD in elementary school are reviewed, and based on this, a direction for developing and applying effective intervention programs is sought.&#x0D; Methods In order to know the research trend of interventional intervention for children with ADHD in elementary school studied in Korea, research literature was searched and papers were selected, focusing on domestic academic journals studied from 2009 to December 2022. For this purpose, 41 selected studies were analyzed according to the thesis analysis framework, and the evidence-based intervention was reviewed by analyzing the qualitative indicators of group-subject studies and single-subject studies.&#x0D; Results As a result of the research analysis, the number of students in the lower grades (1 to 3) was higher than that in the upper grades (4 to 6), and it can be seen that there are many studies targeting boys. In previous studies, there was no detailed description of the intervention site and intervention environment. As for the intervention research program, many art activity-based intervention studies were provided, and analysis according to the dependent variable involved a number of studies on the cognitive and behavioral aspects of children with ADHD. As for the qualitative indicators of group targeting intervention research programs, there was a lack of studies that satisfied performance, operator's information technology, and comparative group's teaching skills. As for the qualitative indicators of single-subject intervention research programs, there were insufficient studies that satisfied the environmental description, description of measurement validity, baseline measurement of the dependent variable, and description of the baseline period.&#x0D; Conclusions The study suggests that intervention studies of children with primary school ADHD need to be designed to increase the reliability and validity of the studies, and to clarify the description of the subjects' intervention environment. Through the results of this study, studies reflecting this should be conducted in the future by considering the evidence-based analysis of the effectiveness and qualitative indicators of interventions for children with ADHD in elementary school.

필라테스가 유방암 환자의 상지 기능, 림프부종, 우울증, 삶의 질에 미치는 영향 : 체계적 고찰연구

Background: Breast Cancer is the leading cause of cancer death. Considering the lifestyle of women with breast cancer, Pilates may be beneficial as a complementary intervention to standard therapeutic exercise. However, few recommendations are available with guidelines for Pilates programs for breast cancer survivors. Objective: This study aims to systematically review previous studies to assess the effects of Pilates on upper extremity function, lymphedema, depression, and quality of life compared to those with other forms of exercise and standard treatment for women with breast cancer. Method: We searched the Cochrane Library, Google Scholar, and Medline via Pubmed for relevant publications through March 2022. The keywords “breast cancer” and “Pilates” were used as keywords, and randomized controlled trials and single-subject studies were included. Results: Thirteen studies were reviewed. Our results show that improvements in the Pilates groups were better than those in groups engaging in home-based exercise or no exercise at all. The Pilates groups showed improvements in upper extremity function including muscle strength, flexibility, and range of motion, as well as improvements in the quality of life score, and reductions in the severity of lymphedema that were greater than other groups. Conclusion: Pilates can complement traditional treatment programs as a safe model. This systematic review provides valuable information for further studies.

장애 및 장애위험 영·유아 대상 긍정적 행동지원 중재연구의 질적 지표 반영 분석: 2011-2021년

The purpose of this study was to review the current research studies’ quality indicators that implemented positive behavior support intervention for young children with a disability and at risk. A total of 42 studies including 28 single subject studies, 9 quasi-experimental studies, and 5 mixed studies from 2011 to 2021 were found as appropriately met the inclusive criteria. Single subject studies were reviewed based on quality indicators that were suggested by Horner et al.(2005) while quasi-experimental studies were reviewed based on them by Gersten et al.(2005). The findings of research synthesis presented that most of SSD studies met the criteria of the quality indicators except result of generalization. Quasi-experimental studies included information of participants, research settings, and intervention implementation while several studies did not include explanation of comparative group, and result measurement. Therefore, implications for future research are discussed to address generalization results for SSD studies and several important quality indicators for quasi-experimental studies in order to provide evidence-based research.

A retrospective cohort analysis of the Yale pediatric genomics discovery program.

The Pediatric Genomics Discovery Program (PGDP) at Yale uses next-generation sequencing (NGS) and translational research to evaluate complex patients with a wide range of phenotypes suspected to have rare genetic diseases. We conducted a retrospective cohort analysis of 356 PGDP probands evaluated between June 2015 and July 2020, querying our database for participant demographics, clinical characteristics, NGS results, and diagnostic and research findings. The three most common phenotypes among the entire studied cohort (n=356) were immune system abnormalities (n=105, 29%), syndromic or multisystem disease (n=103, 29%), and cardiovascular system abnormalities (n=62, 17%). Of 216 patients with final classifications, 77 (36%) received new diagnoses and 139 (64%) were undiagnosed; the remaining 140 patients were still actively being investigated. Monogenetic diagnoses were found in 67 (89%); the largest group had variants in known disease genes but with new contributions such as novel variants (n=31, 40%) or expanded phenotypes (n=14, 18%). Finally, five PGDP diagnoses (8%) were suggestive of novel gene-to-phenotype relationships. A broad range of patients can benefit from single subject studies combining NGS and functional molecular analyses. All pediatric providers should consider further genetics evaluations for patients lacking precise molecular diagnoses.

The effect of PİYAP on piano education of children with autism spectrum disorder

In the research, it is aimed to determine the effect of PİYAP, which is designed to make education effective, fast and easy by embodying an abstract process, on piano education. In the method of the research, multiple probe model among the participants from single-subject studies was applied. In this context, piano training was applied to three children diagnosed with ASD and the effect of PİYAP, which supports the hand position of the participants, on piano education was examined. In this process, in the piano training of the participants; data on the starting level, teaching, end of teaching, follow-up and generalization sessions were obtained. The application of PİYAP, which is used in piano education, in participants with ASD was found to be effective.

Contemporary methods of acquiring patellofemoral joint radiographs: a scoping review

Patellofemoral joint (PFJ) pathology is prevalent and associated with significant morbidity. Although protocols for PFJ radiograph acquisition exist, standardized methods to acquire radiographs of the PFJ have yet to be universally adopted, resulting in variances in patient positioning, weight-bearing status, knee flexion angle, and beam direction, leading to inconsistent joint assessment. We conducted a scoping review of the literature to determine commonly described methods of acquiring PFJ radiographs, and evaluate the methods used in specific settings, disciplines, regions, and for different pathologies. Adhering to PRISMA-ScR guidelines, we searched common databases using keywords related to the concepts of ‘patellofemoral’ and ‘radiograph’. Two independent assessors screened each record for eligibility. Studies published between 2014-2018 describing radiographic acquisition methods of the PFJ were included. Studies of non-human subjects, pediatric populations under 10 years, cadaver studies, and single-subject studies were excluded. Qualitative synthesis of radiographic methods was performed. From 15,053 unique records, 549 articles were included. Four radiographic projections were reported (lateral (84.3% of articles), axial (68.5%), anteroposterior/posteroanterior (66.3%), and lower-limb alignment (21.1%)). We found marked variability for each projection in relation to views acquired (e.g., 13 described axial plane views) and techniques used (e.g., patient positioning, radiograph beam direction). Acquisition techniques varied across disciplines, settings, regions, and pathologies without clear patterns emerging. Our findings highlight considerable variability in PFJ radiograph acquisition methods in contemporary literature. The lack of standardization of PFJ radiograph acquisition may make it difficult to accurately assess and estimate true population prevalence for PFJ pathology.

Constraint-Induced Movement Therapy for Infants With or at Risk for Cerebral Palsy: A Scoping Review.

Although research shows that older children with hemiplegic cerebral palsy (CP) benefit from constraint-induced movement therapy (CIMT), the efficacy of CIMT among the infant population is unknown. To explore the existing evidence on CIMT for infants age 24 mo and younger with CP or at risk for CP. PubMed, CINAHL, Cochrane, and ProQuest were searched. Study Selection and Data Collection: Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and American Occupational Therapy Association guidelines were used for abstracting data and assessing data quality. Two frameworks guided this scoping review. Studies met the following criteria: infants with hemiplegic CP, published in English between 2000 and 2020, peer reviewed, and addressed changes in upper limb function of the hemiplegic upper limb. Eight articles met the inclusion criteria: 2 randomized controlled trials, 1 retrospective cohort design, 1 pretest-posttest study, 2 single-subject studies, and 2 case studies. In this scoping review, we examined CIMT protocols for an overview of dosage, constraint, administration, parent training and education, and objective outcome measures. Existing literature supports CIMT protocols for infants with CP. However, much variability exists in protocol design and appropriate outcome measures among studies. Higher level research is needed to support the efficacy of CIMT among infants with CP. What This Article Adds: This scoping review summarizes the existing literature on CIMT for infants with hemiplegic CP. This information can help guide therapists to implement CIMT protocols in the clinical setting and to identify additional research to establish practice standards.

Daily associations between affect and cognitive performance in older adults with depression and cognitive impairment: a series of seven single-subject studies in the Netherlands

BackgroundComorbidity between depression and cognitive impairment is common in older adults, increases the disease burden disproportionally, and leads to diagnostic uncertainty. Insight into individual daily associations between affect and cognitive performance may help in personalizing diagnosis and treatment decisions. Our objective was to get insight into the daily associations between affect and cognitive performance within individual older adults.MethodsIn this single-subject study seven older adults with both depression and cognitive impairment filled in electronic diaries daily for 62-93 consecutive days evaluating positive affect (PA), negative affect (NA), working memory (WM) and visual learning (VL). Time-series analyses using vector autoregressive modelling, Granger causality tests and cumulative orthogonalized impulse response function analyses were performed for each individual separately.ResultsIn one patient higher NA was associated with better WM the next day. For another patient days with higher NA and lower PA were days with worse WM. For a third patient better VL was associated with lower NA and higher PA the next day. No associations were found for four patients.ConclusionsThese results highlight heterogeneity in the daily associations between affect and cognitive performance and stress the relevance of single-subject studies. These studies may be an important step towards personalized diagnosis and treatment in old age psychiatry.

The Effects of Data-based Instruction (DBI) for Students with Learning Difficulties in Korea: A Single-subject Meta-analysis.

Data-based instruction (DBI) is an ongoing process to utilize students’ data for determining when and how to intensify intervention. It is an educational approach that is suggested as effective to enhance achievements of struggling learners, particularly for those who did not respond to intensive intervention in usual ways. In Korea, DBI was introduced and applied for students with learning difficulties especially since 2000 when the first Korea curriculum-based measurement (CBM) was developed as the name of Basic Academic Skills Assessment. Despite a number of studies accumulated since then, there has been a lack of research that examined the level of evidence-based practice (EBP) of DBI research. Thus, the present study sought to synthesize the DBI research so far in Korea by analyzing the effectiveness of DBI for school-aged students with learning difficulties via meta-analysis and evaluating the quality of the research. In this study, a total of 32 single-subject design studies were used. Multilevel meta-analysis revealed that the mean effect size of DBI was statistically significant (B = 1.34) and there was significant variance across participants in effect sizes. The results from the conditional model showed that exceptionality type, the number of sessions, and the length of each session were significantly accountable for the variability of effect sizes. In addition, the results of the qualitative analysis revealed the acceptable quality of the overall DBI research with some limitations. Based on these findings, implications and study limitations were discussed.

Investigation of Regression-Based Effect Size Methods Developed in Single-Subject Studies.

The purpose of this study is to provide a brief introduction to effect size calculation in single-subject design studies, including a description of nonparametric and regression-based effect sizes. We then focus the rest of the tutorial on common regression-based methods used to calculate effect size in single-subject experimental studies. We start by first describing the difference between five regression-based methods (Gorsuch, White et al., Center et al., Allison and Gorman, Huitema and McKean). This is followed by an example using the five regression-based effect size methods and a demonstration how these methods can be applied using a sample data set. In this way, the question of how the values obtained from different effect size methods differ was answered. The specific regression models used in these five regression-based methods and how these models can be obtained from the SPSS program were shown. R2 values obtained from these five methods were converted to Cohen's d value and compared in this study. The d values obtained from the same data set were estimated as 0.003, 0.357, 2.180, 3.470, and 2.108 for the Allison and Gorman, Gorsuch, White et al., Center et al., as well as for Huitema and McKean methods, respectively. A brief description of selected statistical programs available to conduct regression-based methods was given.

'Single-subject studies'-derived analyses unveil altered biomechanisms between very small cohorts: implications for rare diseases.

MotivationIdentifying altered transcripts between very small human cohorts is particularly challenging and is compounded by the low accrual rate of human subjects in rare diseases or sub-stratified common disorders. Yet, single-subject studies (S3) can compare paired transcriptome samples drawn from the same patient under two conditions (e.g. treated versus pre-treatment) and suggest patient-specific responsive biomechanisms based on the overrepresentation of functionally defined gene sets. These improve statistical power by: (i) reducing the total features tested and (ii) relaxing the requirement of within-cohort uniformity at the transcript level. We propose Inter-N-of-1, a novel method, to identify meaningful differences between very small cohorts by using the effect size of ‘single-subject-study’-derived responsive biological mechanisms.ResultsIn each subject, Inter-N-of-1 requires applying previously published S3-type N-of-1-pathways MixEnrich to two paired samples (e.g. diseased versus unaffected tissues) for determining patient-specific enriched genes sets: Odds Ratios (S3-OR) and S3-variance using Gene Ontology Biological Processes. To evaluate small cohorts, we calculated the precision and recall of Inter-N-of-1 and that of a control method (GLM+EGS) when comparing two cohorts of decreasing sizes (from 20 versus 20 to 2 versus 2) in a comprehensive six-parameter simulation and in a proof-of-concept clinical dataset. In simulations, the Inter-N-of-1 median precision and recall are > 90% and >75% in cohorts of 3 versus 3 distinct subjects (regardless of the parameter values), whereas conventional methods outperform Inter-N-of-1 at sample sizes 9 versus 9 and larger. Similar results were obtained in the clinical proof-of-concept dataset.Availability and implementationR software is available at Lussierlab.net/BSSD.

상황이야기 중재가 ASD 아동 및 청소년의 의사소통 의도에 미치는 효과에 대한 메타연구

Using the meta-analysis, the effect that Social Story intervention has on the communication ability of both children and adolescents with ASD will be investigated. A total of 11 single-subject studies, which were published in Korean academic journals from 2010 to September 2020, were researched by using both selection and exclusion criteria. In the Social Story intervention of ASD children and adolescents, the effect size was examined using the Tau-U value. First, the total effect size of the Social Story intervention on the communication ability was found to be an intermediate effect. Second, the following factors appeared to be associated with a higher effectiveness of Social Story interventions: a) involving elementary-aged participants; b) being in more than 20 intervention sessions; c) using mix(high-tech+low-tech) tools; and d) the implementation in both special education classes and special schools. Among the subcategories of communication ability, the effect size was the highest in the order of social intervention, joint attention, and behavior regulation. Intervention that used Social Story showed an effect on the communication ability of ASD children and adolescents. It was suggested that this effect size may differ, depending on several variables. In addition, the characteristics of Social Story intervention were discussed. Therefore, it is required to both develop and apply a Social Story intervention program for effective intervention in consideration of the relevant variable.

발달지체유아 심리운동 중재 단일대상연구 효과성에 대한 메타분석

본 연구는 단일대상 연구방법으로 수행된 발달지체유아의 심리운동 중재의 효과성을 GetData Graph Digitizer 2.26 프로그램(Tau-U)을 사용하여 객관적이고 체계적으로 분석하는데 목적이 있다. 이를 위해 2008년부터 2020년 12월까지 국내 석·박사 학위논문 및 학술지에 출판된 14편의 전체 평균 효과크기, 유지를 보고하지 않은 한 편을 제외한 13편의 유지 전체 평균 효과크기, 중재변인 평균 효과크기, 중재목적의 평균 효과크기를 분석하였다. 그 결과 첫째, 발달지체유아의 심리운동 중재 단일대상연구의 전체 평균 효과크기는 .67, 유지 전체 평균 효과크기는 .73로 중간 중재 효과로 나타났다. 둘째, 분석대상의 출판 편향은 없었으며 중재변인별로 분석한 결과 출판유형과 중재변인별 효과크기는 유의미한 차이가 없었으며, 전 영역에 대체적으로 효과크기는 높은 것으로 나타났다. 연도별 효과크기는 2008년이 .99로 가장 높게 나타났고, 중재목적의 효과크기는 신체가 .96로 높게 나타났다. 다만, 타당도를 제시하지 않은 연구가 많이 나타나 향후 보강될 필요가 있음을 알 수 있었다. 이와 같이 본 연구에서는 선행된 단일대상연구의 효과성에 대한 메타분석을 통하여 개별연구들의 기초선과 중재구간의 효과크기를 객관적으로 제시하였고, 향후 발달지체유아를 대상으로 한 심리운동 중재 단일대상 연구의 중요성을 부각시켰으며 과학적 연구방향을 모색하였다.

Statistical power: Implications for planning MEG studies

Statistical power is key for robust, replicable science. Here, we systematically explored how numbers of trials and subjects affect statistical power in MEG sensor-level data. More specifically, we simulated "experiments" using the MEG resting-state dataset of the Human Connectome Project (HCP). We divided the data in two conditions, injected a dipolar source at a known anatomical location in the "signal condition", but not in the "noise condition", and detected significant differences at sensor level with classical paired t-tests across subjects, using amplitude, squared amplitude, and global field power (GFP) measures. Group-level detectability of these simulated effects varied drastically with anatomical origin. We thus examined in detail which spatial properties of the sources affected detectability, looking specifically at the distance from closest sensor and orientation of the source, and at the variability of these parameters across subjects. In line with previous single-subject studies, we found that the most detectable effects originate from source locations that are closest to the sensors and oriented tangentially with respect to the head surface. In addition, cross-subject variability in orientation also affected group-level detectability, boosting detection in regions where this variability was small and hindering detection in regions where it was large. Incidentally, we observed a considerable covariation of source position, orientation, and their cross-subject variability in individual brain anatomical space, making it difficult to assess the impact of each of these variables independently of one another. We thus also performed simulations where we controlled spatial properties independently of individual anatomy. These additional simulations confirmed the strong impact of distance and orientation and further showed that orientation variability across subjects affects detectability, whereas position variability does not. Importantly, our study indicates that strict unequivocal recommendations as to the ideal number of trials and subjects for any experiment cannot be realistically provided for neurophysiological studies and should be adapted according to the brain regions under study.