Cited by 1,126Behavioral and Psychological StudiesMeta-analysis and systematic reviewsPsychology Research and Bibliometrics

The DOI matches its Crossref record; 63 of the 65 references it cites were found in a registry or an index.

An improved effect size for single-case research: nonoverlap of all pairs.

Parker, Richard I., Vannest, Kimberly·2009·Behavior Therapy

DOI 10.1016/j.beth.2008.10.006

Open this paper in CoChat — free account

Abstract

Nonoverlap of All Pairs (NAP), an index of data overlap between phases in single-case research, is demonstrated and field tested with 200 published AB contrasts. NAP is a novel application of an established effect size known in various forms as Area Under the Curve (AUC), the Common Language Effect Size (CL), the Probability of Superiority (PS), the Dominance Statistic (DS), Mann-Whitney's U, and Sommers D, among others. NAP was compared with 3 other non-overlap-based indices: PND (percent of nonoverlapping data), PEM (percent of data points exceeding the median), and PAND (percent of all nonoverlapping data), as well as Pearson's R(2). Five questions were addressed about NAP: (a) typical NAP values, (b) its ability to discriminate among typical single-case research results, (c) its power and precision (confidence interval width), (d) its correlation with the established effect size index, R(2), and (e) its relationship with visual judgments. Results were positive, the new index equaling or outperforming the other overlap indices on most criteria.

Integrity signals

Registry

Crossref · 10.1016/j.beth.2008.10.006

Cites

63 of 63 references verified0 citation errors · 0 not checkable

Statistics

Recomputing p-values needs the paper’s full text.

Claims the paper makes

This paper’s full text isn’t openly available, so its claims and self-check weren’t run. The registry and citation checks still apply.

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

Statistical Power Analysis for the Behavioral Sciences
Muller, K. E., & Cohen, J. (1989) · Technometrics · doi:10.2307/1270020 · Cited by 99,603
Statistical power analysis for the behavioral sciences
Cohen, J. (1990) · Computers Environment and Urban Systems · doi:10.1016/0198-9715(90)90050-4 · Cited by 65,417
Statistical Power Analysis for the Behavioral Sciences (2nd ed.).
Lachenbruch, P. A., & Cohen, J. (1989) · Journal of the American Statistical Association · doi:10.2307/2290095 · Cited by 37,421
An analysis of variance test for normality (complete samples)
SHAPIRO, S. S., & WILK, M. B. (1965) · Biometrika · doi:10.1093/biomet/52.3-4.591 · Cited by 23,480
The meaning and use of the area under a receiver operating characteristic (ROC) curve.
Hanley, J. A., & McNeil, B. J. (1982) · Radiology · doi:10.1148/radiology.143.1.7063747 · Cited by 21,856
Practical Nonparametric Statistics
Groggel, D. J., & Conover, W. J. (2000) · Technometrics · doi:10.2307/1271101 · Cited by 11,076
The Use of Single-Subject Research to Identify Evidence-Based Practice in Special Education
Horner, R. H., Carr, E. G., Halle, J., McGee, G., Odom, S., & Wolery, M. (2005) · Exceptional Children · doi:10.1177/001440290507100203 · Cited by 3,368
Robust Tests for the Equality of Variances
Brown, M. B., & Forsythe, A. B. (1974) · Journal of the American Statistical Association · doi:10.1080/01621459.1974.10482955 · Cited by 3,216
Statistical methods in psychology journals: Guidelines and explanations.
Wilkinson, L., & Task Force on Statistical Inference (1999) · American Psychologist · doi:10.1037/0003-066x.54.8.594 · Cited by 2,791
Graphical Methods for Data Analysis.
Healy, M. J. R., Chambers, J. M., Cleveland, W. S., Kleiner, B., & Tukey, P. A. (1984) · Journal of the Royal Statistical Society Series A (General) · doi:10.2307/2981587 · Cited by 2,315

Show all 65 references

Research works printed but not linked: 1

Newson, R. B., 2000. snp15.1: Update to somersd. Stata Technical Bulletin 57: 35. In Stata Technical Bulletin Reprints, vol. 10, 322–323. College Station, TX: Stata Press.

Sorted by citations

Items 701–800 of 1,001

Does validation and alliance during the multimodal investigation affect patients’ acceptance of chronic pain? An experimental single case study
Svanberg, M., Johansson, A., & Boersma, K. (2018) · Scandinavian Journal of Pain · doi:10.1515/sjpain-2018-0051 · Cited by 4
Effects of a Paraphrasing Strategy on the Text Comprehension of Fourth-Grade Striving Readers
Washburn, E. K., Abdullah, S., & Mulcahy, C. A. (2021) · The Elementary School Journal · doi:10.1086/714035 · Cited by 4
“NAP represents the percentage of nonoverlapping data between baseline and intervention phases (Parker & Vannest, 2009).”
BackgroundMethodInfluential
Quantitative Synthesis of Personalized Trials Studies: Meta-Analysis of Aggregated Data Versus Individual Patient Data
Moeyaert, M., & Fingerhut, J. E. (2022) · Harvard data science review · doi:10.1162/99608f92.3574f1dc · Cited by 4
“The nonoverlap of all pairs (NAP; (Parker & Vannest, 2009)) is another measure that was developed for used with personalized trials.”
Systematic review documents PECS effectiveness for exchange-based outcome variables, but effects on speech, social or challenging behavior remain unclear
Wendt, O., & Boesch, M. C. (2010) · Evidence-Based Communication Assessment and Intervention · doi:10.1080/17489531003771753 · Cited by 4
“Better options include the Improvement Rate Difference (Parker, Vannest, & Brown, 2009) or the Non-overlap of All Pairs Index (Parker & Vannest, 2009), which were not available at the time Preston and Carter conducted their review.”
Method
Behavior Interventions in the Restroom: Flushing Away Noise
Pasqua, J. L., Dart, E. H., & Radley, K. C. (2016) · Journal of Applied School Psychology · doi:10.1080/15377903.2016.1183544 · Cited by 4
“Interpretations of NAP results are as follows: weak effects: 0 to .65;medium effects: .66 to .92; large or strong effects: .93 to 1.0” (Parker and Vannest 2009, p. 364).”
BackgroundInfluential
An Investigation of the Efficacy of Speech and Language Interventions with Students with ASD Using Telepractice
Boisvert, M. (2019) · ScholarWorks@UMassAmherst (University of Massachusetts Amherst) · doi:10.7275/h5k7-bw26 · Cited by 4
Intervención en comunicación en el trastorno del espectro autista mediante el programa More than Words . Estudio de caso
Baixauli, I., Gascón, N., Isla, M. D. C., & Diago, C. C. (2018) · Revista de Neurología · doi:10.33588/rn.66s01.2017533 · Cited by 4
Evaluation of low-intensity therapy and parent training for young children with autism based on the early start Denver model
Waddington, H. L. (2018) · doi:10.26686/wgtn.17068478.v1 · Cited by 4
A Preliminary Assessment to Determine the Starting Point for Treatment of Pediatric Feeding Disorders
Patel, M. R., Andersen, A. S., & Patel, V. Y. (2024) · Journal of Developmental and Physical Disabilities · doi:10.1007/s10882-024-09980-6 · Cited by 3
“Nonoverlap of all pairs (NAP; Parker & Vannest, 2009) was calculated to compare the degree of overlap between each data point in baseline and treatment.”
Effect of AAC technology with embedded literacy supports on the participation of children who are emerging symbolic communicators during shared reading
Holyfield, C., Pope, L. E., Semmler, B. J. F., DeLuca, T., Zimmerman, B., Jakobs, E., & Light, J. (2025) · International Journal of Speech-Language Pathology · doi:10.1080/17549507.2025.2499504 · Cited by 3
“The effect size estimation used was nonoverlap of all pairs (NAP; Parker & Vannest, 2009) because it is a precise measure that relates strongly to visual analysis and is commonly used in AAC single case research.”
Influential
Partial-Interval Recording and Estimates of Duration in Meta-analyses: Insights from Self-Monitoring Research
King, S. A., Rodgers, D. B., & Enders, O. G. (2025) · Journal of Behavioral Education · doi:10.1007/s10864-025-09595-7 · Cited by 3
“A conventional nonparametric measure of change between baseline and intervention conditions often accompanying visual analysis (Manolov & Tanious, 2024), NAP estimates nonoverlap between phases, with values ranging from 0 to 1.00 (Parker & Vannest, 2009).”
Influential
Exploring the efficacy of a rational emotive behaviour therapy intervention on football referees: A single case study approach
Carrington, S. C., Turner, M. J., North, J. S., Brady, A., & Martin, E. A. (2025) · Performance Enhancement & Health · doi:10.1016/j.peh.2025.100379 · Cited by 3
Hamstring injury risk in male professional football: do external training loads play a role?
Nilsson, T., Fransson, D., Börjesson, M., Lundblad, M., & Ivarsson, A. (2025) · BMJ Open Sport & Exercise Medicine · doi:10.1136/bmjsem-2025-002649 · Cited by 3
“29 This study, based on the recommendations by Parker and Vannest, 29 used the following benchmarks to interpret the results; 0–0.07 (strong effect in favour of sequence A), 0.08–0.34 (moderate effect in favour of sequence A), 0.35–0.65 (no systematic effect for any of the sequences), 0.66–0.92…”
Influential
Assessment and treatment of pica: A consecutive controlled case series study
Frank‐Crawford, M. A., Hagopian, L. P., Scheithauer, M. C., McMahon, M. X. H., Argueta, T., Call, N. A., & Schmidt, J. D. (2025) · Journal of Applied Behavior Analysis · doi:10.1002/jaba.70035 · Cited by 3
A Meta-analysis of PECS Interventions Using the Improvement Rate Difference
양현규, & Park, W.-H. (2012) · The Journal of Special Children Education · doi:10.21075/kacsn.2012.14.2.73 · Cited by 3
A Systematic Literature Review of Group Contingencies Within General Education Classrooms
Beaver, B. N., Ré, T. C., Griffith, A. K., Zhang, D., & Schoener, M. A. (2023) · Contemporary School Psychology · doi:10.1007/s40688-023-00448-6 · Cited by 3
“Scores between 0 and 0.65 are considered weak effects, scores of 0.66–0.92 are considered moderate effects, and scores of 0.93–1.0 are considered strong effects (Parker & Vannest, 2009).”
Influential
The Relationship between Intercoder Reliability of Data Extraction and Effect Measure Calculation in Single-Case Meta-Analysis
Drevon, D. D., Peart, A. M., & Koval, E. T. (2023) · School Psychology Review · doi:10.1080/2372966x.2023.2273822 · Cited by 3
“In this example, the NAP values based on the actual and extracted data would be interpreted as medium and large, respectively, based on tentative interpretive benchmarks proffered by Parker and Vannest (2009).”
A Family-Based Intervention for Early Elementary Students With Reading and Behavioral Difficulties: A Pilot Study
Roberts, G. J., Capin, P., Handy, A., Coté, B., & Jimenez, Z. (2024) · Journal of Learning Disabilities · doi:10.1177/00222194241263649 · Cited by 3
“To measure the extent to which data overlapped across phases, we calculated two non-overlap effect sizes: non-overlap of all pairs (NAPs; Parker & Vannest, 2009) and Tau-U (Parker et al., 2011).”
Using Virtual Video Modeling Multicomponent Intervention to Improve Mathematical Skills of an Autistic High School Student: Findings From a Two-Experiment Study
Yakubova, G., Defayette, M. A., Gupta, S., Proulx, A. L., & Lee, Y. (2024) · Journal of Special Education Technology · doi:10.1177/01626434241277188 · Cited by 3
“The NAP scores were interpreted using Parker and Vannest (2009) guidelines as the intervention having weak effects (0 – 0.65), medium effects (0.66 – 0.92) and large or strong effects (0.93 – 1.0).”
Influential
Effect of Advanced Footwear Technology Spikes on Sprint Acceleration: A Multiple N-of-1 Trial
Bernuz, B., Laujac, S., Sirial, C., Auffret, S., Preda, C., SLAWINSKI, J. S., Millot, B., Pradon, D., Coudrat, L., & Gavarry, O. (2024) · Sports Medicine - Open · doi:10.1186/s40798-024-00758-w · Cited by 3
“The non-overlap of all pairs (NAP) index [34] was used as the measure of the effect size, with values ranging as follows: small effect (0.5–0.66), medium effect (0.67–0.92), and large effect ( ≥ 0.93).”
BackgroundMethodInfluential
Delivering Enhanced Milieu Teaching to Toddlers With Down Syndrome via Hybrid Telepractice: A Single-Case Experimental Design
Quinn, E. D., Kurin, K., Cook, A., & Kaiser, A. P. (2024) · American Journal of Speech-Language Pathology · doi:10.1044/2024_ajslp-23-00454 · Cited by 3
Preliminary Investigation of Context-Aware Augmentative and Alternative Communication with Automated Just-in-Time Cloze Phrase Response Options for Social Participation from Children on the Autism Spectrum
Holyfield, C., Zimmerman, T. O., MacNeil, S., Caldwell, N., Patel, P. J., Griffen, B., Lorah, E. R., Dragut, E. C., & Vučetić, S. (2024) · Folia Phoniatrica et Logopaedica · doi:10.1159/000542304 · Cited by 3
Investigation of the effectiveness of parent-child interaction therapy on adjustment and behavioral problems in children with subthreshold autism
Seçer, İ., Ulaş, S., Tatlı, E., Çi̇men, F., Bülbül, B., & Tosunoğlu, B. (2025) · Frontiers in Psychology · doi:10.3389/fpsyg.2024.1408847 · Cited by 8
Effectiveness of Video Self-Modeling in Teaching Unplugged Coding Skills to Children with Autism Spectrum Disorders
Kurnaz, E. (2025) · Behavioral Sciences · doi:10.3390/bs15030272 · Cited by 3
“This choice aligns effectively with the graphical analyses commonly utilized in single-subject research (Parker & Vannest, 2009).”
The Two Hearts Mindful Parenting programme for parents of autistic children: a proof-of-concept study
Suvarna, V., Farrell, L. J., Adams, D., Emerson, L., & Paynter, J. M. (2025) · Clinical Psychologist · doi:10.1080/13284207.2025.2498396 · Cited by 6
Rational Emotive Behavior Therapy for exercise: examining self-determined motivation, alongside readiness, confidence, and motivation to exercise
Turner, M. J., Frost, N., Outar, L., O'Connor, H., Tóth, R., Tóth, L., Chadha, N. J., & Wood, A. G. (2025) · Frontiers in Psychology · doi:10.3389/fpsyg.2025.1557885 · Cited by 5
Using deliberate practice for inner skills to enhance therapist In-session mindfulness and presence
Orlowski, E. W., Friedlander, M. L., & Moeyaert, M. (2025) · Counselling Psychology Quarterly · doi:10.1080/09515070.2025.2551710 · Cited by 3
“According to Parker and Vannest (2009), NAP estimates of 0–.31 are weak effects, estimates of .32–.84 are moderate effects, and .85–1 are strong effects.”
Are Schema-Based and Modified Schema-Based Instruction Evidence-Based Practices for Students with Disabilities? A Meta-Analysis
Özkan, Ş. Y., Çakmak, Z., Cevher, Z., Gülboy, E., & Alkoyak, H. Ö. (2022) · Education and Training in Autism and Developmental Disabilities · doi:10.1177/215416472205700408 · Cited by 3
“NAP summarizes data overlap between each phase-A data point and each phase-B data point, respectively (Parker & Vannest, 2009).”
Influential
Effectiveness of earmuffs in protecting hearing during shooting practice: a case-study
Rawool, V. W., & Campbell, C. (2018) · International Journal of Audiology · doi:10.1080/14992027.2018.1441556 · Cited by 3
“Based on expert visual judgments of 200 datasets, Parker and Vannest (2009) suggested following ranges for the NAP index: 0–0.65: weak effects; 0.66–0.92: moderate effects; 0.93–1.0: strong effects.”
BackgroundInfluential
Increasing teacher treatment fidelity to cover, copy, compare through consultation and computer-based implementation planning
Byron, J. R., Sanetti, L. M. H., & Charbonneau, S. (2020) · International Journal of School & Educational Psychology · doi:10.1080/21683603.2020.1753605 · Cited by 3
“In addition, we applied Tau-U, a non-overlap index, following recent recommendations for single-case design (Parker et al., 2014) and interpretive guidelines from Parker and Vannest (Parker & Vannest, 2009; weak = 0 – 0.65, moderate = 0.66 – 0.92, large = 0.93 – 1.00).”
MethodInfluential
Assessing consistency of effects when applying multilevel models to single-case data
Manolov, R., & Ferron, J. M. (2020) · Behavior Research Methods · doi:10.3758/s13428-020-01417-0 · Cited by 3
The effect of contextual interference on the learning of adapted sailing for people with spinal cord injury
Antúnez, R. M., Egea, M. F., Manzanares, A., & Segado, F. (2020) · Adaptive Behavior · doi:10.1177/1059712320946110 · Cited by 3
“Two techniques suitable for analysis of data in single-case designs were utilized: indices of data overlap (non-overlap of all pairs, NAP; Parker & Vannest, 2009) between phases to estimate the size of learning effect (or the magnitude of change) and Jacobson and Truax’s (1991) statistical approach…”
Method
Does Enhanced Conversational Recast promote the learning of grammatical morphemes in Cantonese-speaking preschool children? Answers from a single-case experimental study
Hau, F. F.-W., Wong, A. M.-Y., & Ng, M. W.-Y. (2020) · Child Language Teaching and Therapy · doi:10.1177/0265659020967710 · Cited by 4
“A Tau-U score of 0 to .65 indicates a small effect, .66 to .92 a medium effect, and .93 to 1.00 is a large effect (Parker and Vannest, 2009).”
BackgroundInfluential
Treating Cognitive Symptoms of Generalized Anxiety Disorder Using EMDR Therapy With Bilateral Alternating Tactile Stimulation
de Behrends, M. R. (2021) · Journal of EMDR Practice and Research · doi:10.1891/emdr-d-20-00026 · Cited by 4
Effectiveness of the unified protocol for treating co-morbid health anxiety and depression: an empirical case study
Gaskell, C., Hague, B., & Kellett, S. (2021) · Behavioural and Cognitive Psychotherapy · doi:10.1017/s1352465821000205 · Cited by 3
Understanding the Effect Size of Peer-Mediated Academic Instruction: A Meta-Analysis
Haas, A., Vannest, K. J., Fuller, M. C., & Ganz, J. B. (2021) · Focus on Autism and Other Developmental Disabilities · doi:10.1177/10883576211023329 · Cited by 3
“Again, as with most single-case effect size calculations, NAP does not address trend (Parker & Vannest, 2009).”
BackgroundSelf-citation
Direct Speech-Language Intervention Effects on Augmentative and Alternative Communication System Use in Adults With Developmental Disabilities in a Naturalistic Environment
Hughes, D. M., Vento-Wilson, M. T., & Boyd, L. E. (2022) · American Journal of Speech-Language Pathology · doi:10.1044/2022_ajslp-21-00242 · Cited by 3
Özel Gereksinimli Bireylere Matematik Öğretiminde Somut-Yarı Somut-Soyut Öğretimin Kanıta Dayalı Uygulama Olarak Belirlenmesi
Özlü, Ö., ARSLANOĞLU, A., & Yıkmış, A. (2022) · Ankara Üniversitesi Eğitim Bilimleri Fakültesi Özel Eğitim Dergisi · doi:10.21565/ozelegitimdergisi.938438 · Cited by 3
A Feasibility Trial of Response Contingent Stimulus-Stimulus Pairing to Promote Vocalizations in Minimally Verbal Children Diagnosed with Autism
Shillingsburg, M. A., Bartlett, B. L., Thompson, T. M., McCracken, C., & Scahill, L. D. (2023) · Journal of Developmental and Physical Disabilities · doi:10.1007/s10882-023-09913-9 · Cited by 3
“The average effect size was 0.71 (SD: 0.20; 95% CI [0.64–0.76]), which corresponds to a moderate treatment effect according to NAP interpretive guidelines (Parker & Vannest, 2009).”
Influential
Banking Time
Neuhauser, A., & Mohr, L. (2023) · Schweizerische Zeitschrift für Heilpädagogik/Schweizerische Zeitschrift für Heilpädagogik · doi:10.57161/z2023-04-07 · Cited by 3
Managing middle school students' disruptive behaviors during physical education classes using the color wheel system
Tounsi, O., Trabelsi, O., Souissi, M. A., Koubaa, A., Gharbi, A., Scharenberg, S., Mkaouer, B., & Bahloul, M. (2023) · Psychology in the Schools · doi:10.1002/pits.23060 · Cited by 3
A robot intervention for adults with ADHD and insomnia–A mixed-method proof-of-concept study
Støre, S. J., Tillfors, M., Angelhoff, C., & Norell‐Clarke, A. (2023) · PLoS ONE · doi:10.1371/journal.pone.0290984 · Cited by 4
The Effect of Feasible Coaching Supports on Treatment Fidelity to a MultiComponent Behavioral Intervention
Samudre, M. D., & LeJeune, L. M. (2023) · The Elementary School Journal · doi:10.1086/727227 · Cited by 3
“NAP represents the number of pairs that show no overlap, divided by the total number of comparisons (Parker & Vannest, 2009 ).”
Background
Effect of Banking Time Intervention on Child–Teacher Relationships and Problem Behaviors in China: A Multiple Baseline Design
Zhang, Z., & Wang, Y. (2024) · Behavioral Science · doi:10.3390/bs14030213 · Cited by 3
“If it exceeds 0.93, it signifies a strong effect [43].”
BackgroundInfluential
Neuromuscular electrical stimulation to combat cognitive aging in people with spinal cord injury: protocol for a single case experimental design study
Vints, W. A. J., Levin, O., van Griensven, M., Vlaeyen, J. W. S., Masiulis, N., Verbunt, J., & van Laake‐Geelen, C. C. M. (2024) · BMC Neurology · doi:10.1186/s12883-024-03699-9 · Cited by 3
“The NAP (Nonoverlap of All Pairs) value equals the number of comparison pairs showing no overlap, divided by the total number of comparisons, and can be considered an area under the curve percentage from a receiver operating characteristic analysis [60].”
Method
From mistakes to mastery: An idiographic microanalytical study comparing processes related to effective and ineffective outcomes in behavioral interventions
Pereira, G.-L., Martínez-Díaz, C., García-Morales, R., & Parga, M. X. F. (2024) · Journal of Contextual Behavioral Science · doi:10.1016/j.jcbs.2024.100801 · Cited by 3
Dialectical behavior therapy in the treatment of perfectionism: A Single case design
Sugara, G. S., Puspitawati, A., Arumsari, C., Rahimsyah, A. P., & Muhajirin, M. (2023) · Konselor · doi:10.24036/0202312246-0-86 · Cited by 3
“In assessing the effect size of the single subject intervention calculated using Cohen's d, 0.87 indicates a small effect, 0.87–2.67 indicates a moderate effect, and > 2.67 indicates a large effect (Parker & Vannest, 2009).”
MethodInfluential
Let the eyes do the talking: A scoping review of eye-tracking in paediatric communication assessment and intervention
Hoopmann, L., Bailey, B., & Arciuli, J. (2024) · International Journal of Speech-Language Pathology · doi:10.1080/17549507.2024.2425012 · Cited by 3
“Where possible, standard effect sizes were derived using the formulas and tools of Lenhard and Lenhard (2016) for group design studies and the Nonoverlap of All Pairs (NAP) statistic for single subject design studies as recommended by Parker and Vannest (2009).”
Improving Student On-Task Behavior, Teacher Engagement, and Math Achievement through Blended Learning: A Single-Case Design Study
Johnson, Z. G., Houchins, D. E., Varjas, K., Jimenez, E., & McKinney, T. (2024) · Education and Treatment of Children · doi:10.1007/s43494-024-00140-1 · Cited by 6
“Using methods of calculating effect sizes in single-case design studies (Parker & Vannest, 2009; Pustejovsky, 2015), the calculation of nonoverlap of all pairs (NAP) was carried out by the primary investigator.”
Single-case design and evaluation in R: An introduction and tutorial for school psychologists
McGill, R. J. (2016) · International Journal of School & Educational Psychology · doi:10.1080/21683603.2016.1173610 · Cited by 3
“…users would be greatly benefited by the development of syntax commands for calculating more robust estimators such as nonoverlap of all pairs (NAP; Parker & Vannest, 2009), which can be converted to a nonparametric distribution via the phi coefficient, and regression-based effect sizes that…”
Background
Data-Based Decision Making in School Counseling: Utilizing Multiple Single-Case Indicators to Evaluate Interventions
McGill, R. J., Kennedy, K. S., & Busse, R. T. (2016) · Chapman University Digital Commons (Chapman University) · Cited by 3
The Effects of a Brief Touch Point Intervention for Children With Intellectual Developmental Disabilities (IDD)
Grünke, M., Urton, K., & Karnes, J. (2018) · Journal of Educational and Developmental Psychology · doi:10.5539/jedp.v8n2p187 · Cited by 3
“Such an overall effect size is generally considered as large (Parker & Vannest, 2009; Vannest & Ninci, 2015).”
Background
Systematic review of single case design meta‐analyses for school‐age students with autism spectrum disorders: Current trend and future direction
Zeng, S., Zhao, H., Hu, X., Pereira, B. A., Pan, Q., Chen, M., Reyes, A., & Stone‐MacDonald, A. (2021) · Psychology in the Schools · doi:10.1002/pits.22599 · Cited by 4
Exploring Coaching Strategies in a Parent-Implemented Intervention for Toddlers
Brown, J. A. (2012) · ProQuest LLC eBooks · Cited by 3
Desenhos de investigação de sujeito único em educação especial
Aguiar, C., Moiteiro, A. R., Correia, N. E. F. G., & Pimentel, J. S. (2012) · Análise Psicológica · doi:10.14417/ap.46 · Cited by 3
A Single-Subject Evaluation of the Treatment of Morphing Fear
Zysk, E., Shafran, R., & Williams, T. I. (2017) · Cognitive and Behavioral Practice · doi:10.1016/j.cbpra.2017.03.003 · Cited by 3
Using linear mixed effects models: A single-case experimental design meta-analysis of functional communication training
Sherlock, P., Chezan, L. C., Wolfe, K., Drasgow, E., & Habing, B. (2018) · Evidence-Based Communication Assessment and Intervention · doi:10.1080/17489539.2018.1460902 · Cited by 3
Evidence-Based Treatment
DeRosa, N. M., Sullivan, W. E., & Roane, H. S. (2019) · Autism and child psychopathology series · doi:10.1007/978-3-030-20843-1_27 · Cited by 3
Evaluación de activación conductual en universitarios que consumen mariguana: estudio piloto
Torres, E. S. B., Morales, S. E. C., & Mandujano, J. L. (2021) · Revista Internacional de Investigación en Adicciones · doi:10.28931/riiad.2021.2.02 · Cited by 3
The effects of real-time visual performance feedback on teacher feedback.
Sweigart, C. A. (2015) · doi:10.18297/etd/2082 · Cited by 3
The Effect of Yoga on Attention in Students Diagnosed with ADHD
Petsche, A. (2016) · OpenCommons at University of Connecticut (University of Connecticut) · Cited by 3
You Can Ride Too! An Exploration of the Guided Discovery of Two-wheeled Cycling Skills by Youth with Intellectual Disabilities
Halayko, J. (2014) · ERA: Education and Research Archive (University of Alberta) · doi:10.7939/r3sj19z1n · Cited by 3
Implementation of a brief online skills group of dialectical behaviour therapy for emotional dysregulation in Latinx: a withdrawal experimental single-case design
Muñoz-Martínez, A., Gómez, Y., Naismith, I., & González-Rodríguez, D. (2023) · Behavioural and Cognitive Psychotherapy · doi:10.1017/s1352465823000085 · Cited by 1
“Parker and Vannest (2009) provided the following standards to interpret NAP effect sizes based on the analysis performed with simple phase change and complex phase SCDs: weak (0–0.65), medium (0.66– 0.92), and large (0.93–1.0).”
MethodInfluential
Effects of Horseback Riding on the Postural Control of Autistic Children: A Multiple Baseline Across-subjects Design
Vives-Vilarroig, J., Ruíz-Bernardo, P., & Gómez, A. G. (2024) · Journal of Autism and Developmental Disorders · doi:10.1007/s10803-023-06174-5 · Cited by 4
“For their interpreta - tion, Parker and Vannest (2009, p. 4) examine the size of the”
Single-Subject Study on the Effects of Social Stories on the Social Interaction of a Child with Autism Spectrum Disorder in China
Liu, L., Lei, J., & Wang, C. (2024) · International Journal of Disability Development and Education · doi:10.1080/1034912x.2024.2352375 · Cited by 2
“This study used the non-overlap of all pairs (NAP) method, which has high precision and statistical power (Parker & Vannest, 2009), to assess the intervention effectiveness of social stories on social interaction.”
The Effectiveness of Modified Conceptual Model-Based Problem-Solving in Teaching Word Problem-Solving Skills to Students with Specific Learning Disabilities
Özlü, Ö., & Yıkmış, A. (2024) · Ankara Üniversitesi Eğitim Bilimleri Fakültesi Özel Eğitim Dergisi · doi:10.21565/ozelegitimdergisi.1443417 · Cited by 2
Piloting an approach to family-implemented decoding instruction for kindergarten-aged children
Hall, C., Dahl‐Leonard, K., Roberts, G. J., Capin, P., Peacott, D., Thayer, L., & Conradi, K. (2025) · Early Childhood Research Quarterly · doi:10.1016/j.ecresq.2025.02.011 · Cited by 2
Effect of explicit literacy instruction on letter-sound correspondence acquisition for a child with cerebral palsy who uses AAC eye gaze
Caron, J. G., Ryan, N., Babb, S., Holyfield, C., & O’Brien, M. (2025) · Augmentative and Alternative Communication · doi:10.1080/07434618.2025.2466166 · Cited by 2
“…rate differences (iRD) were also computed as an effect size indicator; iRD scores greater than 0.75 were considered very large effect sizes (Parker & vannest, 2009). an online iRD calculator was used to calculate iRD (vannest et al., 2011). to ensure the integrity and consistency of data…”
Influential
Using Self-Management to Teach Social Interactions to Preschoolers with Autism Spectrum Disorder During Recess in School Settings
Galanis, P., & Gena, Α. (2025) · Education Sciences · doi:10.3390/educsci15050587 · Cited by 2
Effects of the Accelerating Mathematics Performance With Practice Strategies (AMPPS) Intervention Program When Delivered During Summer in a One‐On‐One Virtual Format
Newson, N. K., Begeny, J. C., Wang, J., Jordán, Y. P., Codding, R. S., & Kromminga, K. R. (2025) · Psychology in the Schools · doi:10.1002/pits.70034 · Cited by 2
“Interpretation of NAP effect sizes are as follows: weak (0 – 0.65), medium (0.66 – 0.93), and large (0.94 – 1.00; Parker and Vannest 2009).”
Influential
Using point-of-view video modelling with young autistic students: a systematic literature review
Moustaka, M., Kossyvaki, L., & Terlektsi, E. (2025) · International Journal of Developmental Disabilities · doi:10.1080/20473869.2025.2533936 · Cited by 3
Analysis of Treatment Effect Indices Used in Counseling Single Case Research
Brown, C. L., Turner, R. C., Peltier, C. J., Lo, W., Christian, D. D., & Smarinsky, E. C. (2025) · Measurement and Evaluation in Counseling and Development · doi:10.1080/07481756.2025.2531834 · Cited by 2
“…by Peltier et al. (2024) systematic review of 50 SCRD counseling studies, where 46% reported PEM and 24% reported PND. Nonoverlap of all pairs (NAP; Parker & Vannest, 2009) and Tau/Tau-U (Parker, Vannest, Davis, & Sauber, 2011) were developed later in time, however counseling researchers reported…”
Can a virtual reality exposure therapy app improve symptoms of Emetophobia? A single-subject Experimental design study
Wallace, R., Lacey, C. J., & Sargisson, R. J. (2025) · Journal of Behavior Therapy and Experimental Psychiatry · doi:10.1016/j.jbtep.2025.102056 · Cited by 3
Synthesizing Single-Case Experimental Designs: Modeling Complex Data Structures
Cheng, K., Yi, Z.-Y., Moeyaert, M., Beretvas, S. N., den Noortgate, W. V., & Ferron, J. M. (2025) · Journal of Behavioral Education · doi:10.1007/s10864-025-09602-x · Cited by 2
N‐of‐1 trials in clinical research: Methodological foundations, statistical approaches and implementation challenges
de Carvalho, M. C. L., Simões, M. D. M. D., Adler, U., Viana, A. B., de Sousa, C. N. S., & Sanders, L. L. O. (2025) · British Journal of Clinical Pharmacology · doi:10.1002/bcp.70382 · Cited by 4
“Several effect size measures for SCEDs exist, such as the Nonoverlap of All Pairs (NAP), 49 Percent of Non-overlapping Data (PND) 50 and between-case Standardized Mean Difference.”
Using a Socially Assistive Robot to Improve Attention in Children with Autism During Academic Instruction
Halkowski, M., Kubina, R. M., Leitao, N. D. L., & Winn, K. (2026) · International Journal of Social Robotics · doi:10.1007/s12369-026-01380-4 · Cited by 2
GRAPE Model of Rational Emotive Behavior Coaching for Growth Mindset and Academic Resilience
Sugara, G. S., Payza, R. Z., Muhajirin, M., & Rahimsyah, A. P. (2026) · Journal of Rational-Emotive & Cognitive-Behavior Therapy · doi:10.1007/s10942-026-00691-9 · Cited by 2
“This provides additional insights into the intervention’s impact on the target variable (Parker & Vannest, 2009 ).”
Efficacy of Parent-Child Interaction Therapy with the Use of In-Room Coaching
Reeve, C. A., Dukes, C., Damashek, A. L., & Gaynor, S. T. (2025) · Child & Family Behavior Therapy · doi:10.1080/07317107.2025.2589753 · Cited by 2
“Tentative interpretive ranges for non-overlap of all pairs analyses are: 0–.65 = small effect size, .66–.92 = medium effect size, and .93–1.00 = large effect size (Parker & Vannest, 2009).”
Influential
Using a Hero as a Model in Video Instruction to Improve the Academic Performance of a Student with Autism Spectrum Disorder: A Case Study
Ohtake, Y. (2016) · Institutional Repositories DataBase (IRDB) · doi:10.18926/bgeou/54228 · Cited by 2
Effects of Computerized Social Skills Instruction for At-Risk Adolescents
Vernon, D. S., & Schumaker, J. B. (2021) · Journal of Special Education Technology · doi:10.1177/0162643421997043 · Cited by 2
“In addition, the Nono-verlap of All Pairs (NAP) statistic (Parker & Vannest, 2009) was calculated along with Tau U for the effect size.”
Method
Evaluation of Low-intensity Therapist-Delivered Intervention in Addition to Parent Coaching for Young Children with Autism Spectrum Disorder
Waddington, H. L., Curtis, S., van Noorden, L. E., Sigafoos, J., van der Meer, L. A. J., & Whitehouse, A. (2022) · International Journal of Disability Development and Education · doi:10.1080/1034912x.2022.2120601 · Cited by 2
“…statistic was calculated to determine the effect size of improvements from parent coaching baseline to: (a) parent coaching, (b) direct therapy baseline, (c) direct therapy, and (d) maintenance for parent fidelity and the three child dependent variables with the parent (Parker & Vannest, 2009).”
Method
Vehicle noise: comparison of loudness ratings in the field and the laboratory
Llorach, G., Oetting, D., Vormann, M., Meis, M., & Hohmann, V. (2022) · International Journal of Audiology · doi:10.1080/14992027.2022.2147867 · Cited by 2
“…loudness perception ratings were analysed with two different approaches: metric-model analysis (repeated-measures ANOVA and Bonferroni-corrected pairwise comparisons) and ordinal analysis (non-overlap of all pairs (NAP) (Parker and Vannest 2009) and group comparisons with Mann – Whitney U tests).”
Method
Training arithmetical skills when finger counting and working memory cannot be used: A single case study in a child with cerebral palsy
Neveu, M., Geurten, M., & Rousselle, L. (2023) · Applied Neuropsychology Child · doi:10.1080/21622965.2023.2170798 · Cited by 3
“Non-overlap of All Pairs scores (NAP-scores) were calculated to compare performance (Parker & Vannest, 2009).”
MethodInfluential
Short-term intervention complemented by wearable technology improves Trichotillomania – A naturalistic single-case report
Leibinger, K., Murray, E., Aschenbrenner, S., & Randerath, J. (2023) · Frontiers in Psychology · doi:10.3389/fpsyg.2023.1071532 · Cited by 2
“According to the interpretation guidelines by Parker and Vannest (2009), this index (Tau-U = − 0.4791, Z = − 2.533, p = 0.011) is in the range of medium effect sizes ( ∣ 0.32–0.84 ∣ ).”
MethodInfluential
Exploring Single-Case Research Design With Individualized Anxiety-Based Neurofeedback Protocols and Session Data
Gregory, J. C., Romero, D. E., & Jones, M. S. (2023) · NeuroRegulation · doi:10.15540/nr.10.3.159 · Cited by 2
Multiple baseline and multiple probe design studies targeting academic skills: Trends over time in effect sizes
Zink, H. H., Norman, E. R. V., & Klingbeil, D. A. (2023) · Psychology in the Schools · doi:10.1002/pits.23120 · Cited by 2
Empowering patients with persistent pain: The potential of cognitive functional therapy in interdisciplinary care: A single-case experimental design
Zingg, S., de Graaf, M., & Hilfiker, R. (2023) · Journal of Bodywork and Movement Therapies · doi:10.1016/j.jbmt.2023.11.063 · Cited by 2
Behavior Change Potential of Classroom Behavior Management Mobile Applications: A Systematic Review
Mittiga, S. R., Freeman, N. C., Leif, E., Furlonger, B., & Pattison, E. (2024) · Education and Treatment of Children · doi:10.1007/s43494-024-00122-3 · Cited by 2
“Low NAP values ( 0.66) suggest weak or no evidence of an effect (Parker & Vannest, 2009).”
Influential
School staff delivery of a solution focused intervention to support pupils' behaviour
Watson, E., & Hayes, B. (2024) · Support for Learning · doi:10.1111/1467-9604.12471 · Cited by 2
“%) effects (Parker & Vannest, 2009).”
Teaching Constant Rate-of-Change Problem-Solving to Secondary Students With or at Risk of Learning Disabilities
Bundock, K., Callan, G. L., McClain, M. B., Benney, C. M., Longhurst, D. N., & Rolf, K. R. (2024) · Journal of Learning Disabilities · doi:10.1177/00222194241254094 · Cited by 2
“…between each baseline phase data point and each intervention phase data point) provides a case-level effect size that is highly correlated with R 2 (Parker & Vannest, 2009), and LRR (a metric that compares two mean levels) provides a comparison of level change between baseline and intervention and…”
Decreasing inappropriate comments and interruptions during social interactions in an adolescent with a level one autism spectrum disorder diagnosis
VanderWoude, T., & Ripple, H. E. (2024) · Research in Autism · doi:10.1016/j.rasd.2024.102429 · Cited by 2
Online Intervention to Prevent Summer Learning Loss For Struggling First Grade Writers
Klein, P. D., Casola, M., Dombroski, J., Shaw, K., & Thompson, S. C. (2024) · Reading & Writing Quarterly · doi:10.1080/10573569.2024.2389795 · Cited by 1
“For comparing the level of scores between phases for each participant, we report Nonoverlap of All Pairs (NAP; Parker & Vannest, 2009).”
The Effects of Using Adapted Science eBooks Within Shared Reading on Comprehension and Task Engagement of Students with Autism Spectrum Disorder
Kim, S.-Y., Rispoli, M. J., Mason, R. A., Lory, C., Gregori, E. V., Roberts, C. A., Whitford, D. K., & Wang, D. (2024) · Journal of Autism and Developmental Disorders · doi:10.1007/s10803-024-06525-w · Cited by 2
“Tau-U ranges from 0 to 1 and is interpreted as small effects (i.e., 0–0.65), medium effects (i.e., 0.66–0.92), or large effects (i.e., 0.93–1.0) (Parker & Vannest, 2009 ).”
Influential
Sensory Enhanced Interactive Storytelling Technique (SEIS-T): Supporting Active Communication Through Short, Multimodal Narratives
Wolters-Leermakers, N., van Wingerden, E., Gerkema-Nijhof, R., & van Balkom, H. (2024) · International Journal of Disability Development and Education · doi:10.1080/1034912x.2024.2408673 · Cited by 2
“A small treatment effect is represented by a NAP percentage between 0% and 65%, whereas 66–92% reflects a medium effect, and 93–100% a large effect (Parker & Vannest, 2009).”
Effectiveness of a Person-Centered Interdisciplinary Rehabilitation Treatment of Post–COVID-19 Condition: Protocol for a Single-Case Experimental Design Study
Wiertz, C. M. H., van Meulenbroek, T., Lamper, C., Hemmen, B., Sep, S. J. S., Huijnen, I. P. J., Goossens, M. E. J. B., Burgers, J. S., & Verbunt, J. (2024) · JMIR Research Protocols · doi:10.2196/63951 · Cited by 2
“It can be calculated as an area under the curve [60].”
BackgroundInfluential
Pilot study protocol evaluating the impact of telerobotics interactions with autistic children during a Denver intervention on communication skills using single-case experimental design
Fournier, C., Michelon, C., Granit, V., Audoyer, P., Bernardot, A., Picot, M., Kheddar, A., & Baghdadli, A. (2024) · BMJ Open · doi:10.1136/bmjopen-2024-084110 · Cited by 2
Technology based self-monitoring for a student with EBD to improve academic engagement
Maxcy, L., Soares, D. A., & Harrison, J. R. (2025) · Contemporary Educational Technology · doi:10.30935/cedtech/15864 · Cited by 2
Pairing phrase‐cued text with readers theatre: Effects on reading prosody and automaticity
Rodgers, E. M., D’Agostino, J. V., Levin, J. R., & Rasinski, T. V. (2025) · Journal of Research in Reading · doi:10.1111/1467-9817.70002 · Cited by 2
The Effectiveness of Video Visual Scene Display-Assisted Behavioral Skills Training in the Instruction of Skills to Prevent Online Sexual Abuse Among Adults with Autism Spectrum Disorder
Oğur, Ç., & Olçay, S. (2025) · Archives of Sexual Behavior · doi:10.1007/s10508-025-03152-z · Cited by 2
“Individuals with ASD are four to eight times more exposed to sexual abuse when compared to individuals with typical development (McDaniels & Fleming, 2016) due to communication difficulties such as denial or asking for help (Edel-son, 2010), inability to recognize the social cues that could allow them to differentiate…”
Influential
Using Functional Analytic Psychotherapy to Address Interpersonal Difficulties With a Neurodiverse, Non-Binary Client
Robayo, S., Velandia-Alarcón, C., García, Y., Skinta, M., & Muñoz-Martínez, A. (2025) · Clinical Case Studies · doi:10.1177/15346501251407940 · Cited by 1
“Data were analyzed combining visual inspection (level, trend, variability, immediacy of change) with the Non-Overlap of All Pairs (NAP) index (Parker & Vannest, 2009), a non-parametric statistic of effect size.”

Authors: Parker, R. I., & Vannest, K.
Affiliations: Texas A&M University (US)
Corresponding author: Parker, Richard I.
ORCID: Vannest, Kimberly
Venue: Behavior Therapy
Publisher: Elsevier BV
Published: 2009-12
Volume: 40
Issue: 4
Pages: 357-367
ISSN: 0005-7894 (ISSN-L)
DOI: 10.1016/j.beth.2008.10.006
OpenAlex: W2028628292
Cited by: 1,126
References: 65
Citations by year: 2026: 61 · 2025: 95 · 2024: 85 · 2023: 97 · 2022: 99 · 2021: 90 · 2020: 87 · 2019: 81 · 2018: 86 · 2017: 84 · 2016: 69 · 2015: 57 · 2014: 49 · 2013: 30 · 2012: 35
FWCI: 12.23
Type: journal article
Language: en
Open access: closed
Licence: www.elsevier.com/tdm/userlicense/1.0/ (tdm)
Locations: Behavior Therapy (publishedVersion)
PubMed (publishedVersion)
Topics: Social Sciences › Psychology › Developmental and Educational Psychology › Behavioral and Psychological Studies
Social Sciences › Decision Sciences › Statistics, Probability and Uncertainty › Meta-analysis and systematic reviews
Social Sciences › Psychology › Experimental and Cognitive Psychology › Psychology Research and Bibliometrics
Keywords: effect size, single subject research, data overlap, R-squared, visual assessment, confidence interval width, statistical power
MeSH terms: Humans, Models, Psychological, Probability, Psychology, Research Design, Confidence Intervals, Area Under Curve

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review

An improved effect size for single-case research: nonoverlap of all pairs.

Abstract

Overview

Integrity signals

Verification

Claims the paper makes

Claims other papers make about this one

Citations

Cites

Cited by

Related

Metadata

Record

About these checks