O.T. Wizard Clinical Research Series

89% Improved. Five Domains Exceeded Natural Growth. Here Is What the Data Shows.

Measuring Pediatric OT Outcomes Above the Threshold of Natural Maturation

By Stephanie Seymore Wick, MSOT, OT/L | Founder and Clinical Architect, O.T. Wizard

Introduction

Every pediatric occupational therapist knows that the work they do matters. The harder question is whether the profession can show, in precise and reproducible terms, how much it matters. For decades, OT documentation has been built around goals, progress notes, and clinical narratives. These tools record care. They rarely measure change in a way that separates what the child gained through intervention from what developmental maturation would have produced on its own.

This report addresses that gap directly. Using O.T. Wizard, a clinical intelligence system designed to generate structured, reproducible, multi-domain assessment data for pediatric OT practice, we examined functional performance change across eight domains in 71 preschool-aged children who completed two full evaluations an average of 4.85 months apart.

The central question throughout this analysis is not simply whether children improved. The meaningful question is whether the children in this cohort improved beyond what developmental maturation alone would have produced over the same interval. A natural growth correction applied consistently throughout this report makes that distinction explicit in every finding.

This is the expanded replication of a February 2026 analysis of 44 paired evaluations. The findings across the 27 additional pairs are consistent with and strengthen the earlier report across all domains. The core story does not change with more data. It becomes more precise.

Study Sample

Age Distribution

The longitudinal cohort consisted of 71 preschool-aged children, each with two complete O.T. Wizard evaluations separated by a minimum of 30 days. The mean inter-evaluation interval was 4.85 months (approximately 148 days), with a range of approximately 37 to 173 days. Mean age at first evaluation was 53.5 months.

Starting age band distribution: Band G (36 to 47.99 months, n=6), Band H (48 to 53.99 months, n=29), Band I (54 to 59.99 months, n=33), and Band J (60 to 65.99 months, n=3). Bands H and I together represent 87% of the sample and are the primary basis for findings reported here. Bands G and J are included in the data but interpreted with caution given their smaller sizes.

Demographics and Clinical Status

All assessments were conducted in North Carolina through the O.T. Wizard clinical platform. Consistent with the broader software dataset, at least 90% of children qualified for Medicaid, and for many, the structured evaluation environment represented an early introduction to formal educational or clinical settings. Primary language was English for 90% of children, with 9% Spanish-speaking and 1% other. All children had been recommended for occupational therapy services following developmental screening failure.

It is important for readers to interpret these findings within this clinical context. This is not a typically developing population. These are children with identified developmental concerns who were referred for and receiving skilled OT services. Outcome findings therefore reflect the response of a clinically referred, predominantly low-income sample to structured early intervention, not population-level developmental norms.

Natural Growth Framework

Before examining domain-level findings, it is necessary to establish what score change we would expect to observe in the absence of intervention. Children in this cohort averaged 53.5 months of age at first evaluation and were reassessed approximately 4.85 months later. On a well-constructed developmental scale, maturation alone would be expected to produce a gain proportional to that age progression.

The natural growth rate for this cohort is calculated as the mean inter-evaluation interval divided by the mean age at Evaluation 1: 4.85 months divided by 53.5 months equals 9.2%. This figure represents the expected score improvement attributable to developmental maturation alone over the study period.

This natural growth rate serves as the reference threshold throughout this report. Domain gains below 9.2% suggest performance did not keep pace with chronological age progression. Gains at 9.2% suggest maturation-equivalent growth. Gains above 9.2% represent functional improvement beyond what age progression alone would predict.

This correction is transparent, reproducible, and requires no external normative sample to apply. It is a direct arithmetic relationship between age progression and scale progression on a fixed instrument. The Gain Above Natural column in each table makes this comparison explicit.

Research Hypotheses

Three primary hypotheses guided this analysis. First, children receiving occupational therapy services would demonstrate composite score gains substantially exceeding the 9.2% natural growth threshold. Second, domains most directly targeted by OT in preschool settings, specifically visual motor integration, fine motor skills, visual perception, and activities of daily living, would show the largest gains above expected growth. Third, Band H children (48 to 53.99 months) would demonstrate greater gains than Band I children, reflecting greater developmental sensitivity at a younger starting point.

Literature Review and Context

The preschool years represent a critical period for fine motor and visual motor development. Between the ages of three and five, neuromotor pathways underlying pencil control, bilateral coordination, and hand specialization undergo rapid maturation, establishing the foundation for academic skill development. Handwriting readiness, scissor use, and self-care independence all draw from skill sets that are most efficiently built during this developmental window.

Visual motor integration has consistently been identified as one of the strongest predictors of kindergarten handwriting readiness. Daly and colleagues (2003) found VMI performance at preschool age predicted handwriting speed and legibility at ages six and seven with effect sizes exceeding those of fine motor or visual perception measures alone. Duff and colleagues (2015) demonstrated that children with developmental coordination difficulties who receive targeted fine motor intervention during the preschool years show significantly better handwriting outcomes at school entry than matched peers without services. It is equally important to recognize that VMI does not operate in isolation as a predictor of handwriting development. Emergent literacy skills, particularly alphabet knowledge, letter-sound awareness, and early orthographic processing, are also well-established predictors of handwriting fluency and transcription accuracy (Gerde et al., 2025; Puranik et al., 2011). The relationship between literacy exposure and VMI development is bidirectional: children who are actively engaged in letter-learning and pre-writing activities in preschool settings are simultaneously building the visual discrimination, directionality, and motor planning foundations that underlie VMI performance. This intersection is clinically relevant and is acknowledged as a study limitation below.

The measurement infrastructure required to track these outcomes longitudinally has historically been a limiting factor in OT outcomes research. Standard evaluation protocols typically capture a single snapshot of performance, and re-evaluation data, when it exists, is rarely structured for computational comparison. O.T. Wizard was designed to address this gap, enabling structured, reproducible, multi-domain measurement within the constraints of a standard clinical evaluation and supporting longitudinal outcome tracking that traditional paper-based protocols do not practically support.

This report also extends a prior O.T. Wizard longitudinal analysis (Wick, 2026) that examined 44 paired evaluations from the same clinical platform. The expanded sample of 71 pairs presented here confirms and extends those findings with consistent direction and strength across all eight domains assessed.

Key Findings

Overall Composite Performance

Across all 71 children with valid paired evaluations, mean composite score increased from 519.8 at Evaluation 1 to 646.0 at Evaluation 2, a mean raw gain of 126.2 points. Against the 9.2% natural growth expectation, the expected gain for this cohort was approximately 47.6 points. The observed gain exceeded the natural growth threshold by 78.6 points, representing 165% above expected developmental progress. To be precise about what that means: for every point of progress that natural maturation would have produced, these children gained 2.65 points. They moved forward at more than two and a half times the rate that developmental aging alone would have driven. That is not incremental. That is intervention doing exactly what skilled, structured, early occupational therapy is designed to do.

The gain was highly statistically significant (paired t-test, t=10.62, p<0.001, Cohen’s d=1.26, large effect). 89% of children showed improvement at the second evaluation. 42% of children began below the 500-point composite threshold; by Evaluation 2, only 17% remained below that threshold. Twenty children crossed the functional midpoint of the scale during the study interval.

Domain-Level Results

The following table presents results across all eight assessed domains, sorted by magnitude of gain above natural growth. All scores are pre-Rasch ordinal percentage values expressed as points within each domain’s maximum possible score. Natural Gain represents the expected gain based on the 9.2% natural growth rate applied to each domain’s Evaluation 1 mean.

Table 1. Domain-level longitudinal comparison. Scores are points within each domain’s maximum possible score. Natural Gain = Eval 1 mean x 9.2% natural growth rate. Above Natural = Raw Gain minus Natural Gain. Effect sizes: Large (d>0.8), Medium (d>0.5). Executive Functioning, Participation, and Praxis findings are addressed in the discussion section. All scores are pre-Rasch raw values.

Visual Motor Integration produced the largest gain above expected growth in the dataset, rising from 37.6 to 62.2 points, a raw gain of 24.6 points against an expected natural gain of 3.4 points. The gain above natural growth was 21.1 points, representing 614% above what maturation alone would have produced. 94% of children with VMI scores showed improvement. The effect size of d=1.49 is considered large by conventional standards.

Activities of Daily Living showed a raw gain of 23.7 points against a natural expectation of 4.2 points, placing the gain above natural growth at 19.5 points (468% above expected). Fine Motor Skills showed 11.6 points above the natural expectation (268% above expected, d=1.00, large). Gross Motor Skills showed 10.3 points above expected (198% above expected, d=0.77, medium). Visual Perception showed 6.7 points above expected (118% above expected, d=0.74, medium).

Praxis, Participation, and Executive Functioning showed gains at or below the natural growth threshold, none with statistically significant large effects. The interpretation of these findings requires clinical context and is discussed in detail below. A dedicated companion analysis of the Participation and Executive Functioning longitudinal findings is forthcoming in this research series, as the novelty effect hypothesis and its implications for clinical documentation merit extended treatment.

Performance by Starting Age Band

The following table presents composite score change by starting age band. Natural growth rates vary slightly by band because younger children have a larger age progression ratio over the same elapsed time. Bands G and J are included for completeness but should be interpreted with caution given small sample sizes.

Table 2. Composite score change by starting age band. NGR = natural growth rate (months elapsed / age at Eval 1). Above Natural = Raw Gain minus (Eval 1 mean x NGR). Bands G and J interpreted with caution (small n).

Band H children (ages 48 to 53.99 months) showed the largest absolute gains above natural growth, averaging 84.8 points above the natural expectation on a composite gain of 134.8 points. Band I children showed 81.9 points above expected on a composite gain of 127.5 points. Both primary age bands show gains well above the natural growth threshold, and the difference between them is modest. This is broadly consistent with the earlier 44-pair analysis, which found Band H slightly outperforming Band I. The 48 to 54 month window continues to appear as a period of high clinical yield for OT service delivery, though both bands show substantial responsiveness.

Understanding the Flat Domains: Praxis, Participation, and Executive Functioning

Three domains showed gains at or below the natural growth threshold: Praxis (-6%), Participation (-30%), and Executive Functioning (-57%). These findings are clinically important to interpret carefully, as they do not simply mean that OT failed to produce change in these areas.

For Praxis, the near-zero gain is more likely a reflection of current measurement sensitivity than true insensitivity to intervention. Praxis is a complex, context-dependent construct requiring the integration of motor planning, bilateral coordination, and sequencing across novel tasks. Detecting incremental praxis development over a five-month interval likely requires either longer measurement windows or more precisely calibrated items. Rasch calibration of the praxis item bank is a priority in the continuing research agenda.

Participation and Executive Functioning tell a more nuanced story that involves the measurement context itself. Both domains are rated by the therapist based on behavioral observation during the evaluation. At Evaluation 1, the child is meeting the therapist for the first time. The novelty of the interaction, the structured environment, and the desire to engage with an unfamiliar adult may produce elevated ratings that reflect situational compliance rather than the child’s authentic behavioral baseline. By Evaluation 2, the therapeutic relationship is established and the child is comfortable enough to reveal their genuine regulatory and engagement patterns, including the variability and difficulty that characterize their daily functioning. If Evaluation 1 ratings are systematically elevated by this novelty effect, the apparent absence of gain at Evaluation 2 reflects a measurement context shift rather than a failure of intervention. A dedicated research blog on the novelty effect hypothesis and its implications for clinical documentation is forthcoming in this series.

Correlation Analysis

A moderate negative correlation was observed between starting composite score and magnitude of change (consistent with the 44-pair analysis). Children who began with lower scores tended to show larger gains. This regression-to-the-mean effect is expected in clinical samples and does not invalidate the findings, but is an important interpretive consideration. No significant correlation was found between inter-evaluation interval length and change score, indicating that the range of intervals in this cohort (approximately 37 to 173 days) did not materially influence the magnitude of observed gains.

Implications for OT Practice

The domain-level findings interpreted through the natural growth framework allow occupational therapists to make specific, evidence-informed decisions about evaluation and intervention priorities. Five domains showed gains ranging from 118% to 614% above the 9.2% natural growth threshold, all with statistical significance and large or medium effect sizes. These gains were achieved in a predominantly Medicaid-qualifying, low-income clinical population with significant developmental concerns, which makes the magnitude of change all the more clinically meaningful.

For insurance authorization and educational planning, the natural growth framework provides a communication tool that is both precise and accessible. Rather than reporting a raw score change, the practitioner can state that the child’s VMI performance exceeded the expected developmental rate by 21.1 points over approximately five months, providing clear evidence that skilled OT intervention, not maturation, drove the observed change. This framing is methodologically transparent and directly responsive to the medical necessity standards that payers apply.

The composite score threshold finding carries particular weight for authorization purposes. A child who begins services below the 500-point composite threshold and crosses it during the authorization period has demonstrated objectively measurable functional change. Of the 30 children who began below 500 points, 20 crossed that threshold during the study interval. That is a two-thirds success rate in moving children from below-threshold to at-threshold performance within a single authorization period.

Serial assessments using a consistent instrument also generate slope data that goes beyond a single outcome comparison. The rate of gain above natural growth, calculated at the domain level, can be used to project whether a child is on track to reach functional goals within a given authorization period, supporting proactive communication with payers and educational teams before a plateau needs to be explained rather than after.

Implications for Intervention Planning

The convergent large effect sizes across VMI, ADL, Fine Motor, and Gross Motor domains point toward a functional skill cluster that is highly responsive to structured OT programming during the preschool developmental window. These four domains share underlying requirements for postural control, bilateral coordination, and visually guided hand movement. Interventions that integrate these components across functional activities are supported by both the data pattern and established OT theory.

The Gross Motor finding is particularly relevant for intervention sequencing. A gain of 10.3 points above natural expectation with a medium-to-large effect confirms that proximal postural and movement foundations are responsive to OT services alongside distal fine motor work. For children showing limited fine motor or VMI gains, postural foundation and gross motor assessment should be considered before concluding that the upper extremity is the primary limiting factor.

For children whose evaluation profiles show strength in Gross Motor relative to Fine Motor and VMI, a proximal-to-distal intervention sequence may accelerate gains across the entire cluster. The strength of the ADL finding (d=1.27) reflects the functional integration that OT uniquely provides: when children gain in fine motor, VMI, and postural control simultaneously, daily living skills follow as a natural downstream effect.

The flat findings for Praxis, Participation, and Executive Functioning should not reduce the clinical attention given to these areas. They reflect current measurement constraints rather than evidence of non-response to intervention. Goal writing in these domains should continue, supported by structured therapist observation and emerging platform tools designed to capture behavioral change over longer intervals.

Study Limitations

This study carries several important limitations that readers should consider when interpreting and applying the findings.

The sample is clinical and geographically restricted to North Carolina. Findings cannot be generalized to typically developing children or to populations in other regions with different demographic profiles, service delivery models, or referral criteria. The absence of a control group means observed gains cannot be causally attributed to OT intervention. Natural maturation, regression to the mean, and test familiarity effects each contribute to observed change scores to an unknown degree.

The 9.2% natural growth correction is a methodologically transparent estimate derived directly from the age progression of this cohort on this instrument. It assumes proportional developmental scaling across the score range, an assumption that Rasch calibration will allow us to test empirically. Future work with a typically developing comparison group will allow domain-specific, empirically derived growth expectations to replace this uniform estimate.

The regression-to-the-mean effect means that domains with the lowest Evaluation 1 scores (VMI, ADL, Fine Motor) also showed the largest gains. The true intervention effect within these domains is likely substantial, but the proportion attributable to treatment versus regression toward the mean cannot be fully separated without a control group. All scores remain pre-Rasch ordinal percentage values. Statistical analyses were generated with AI-based analytical tools and reviewed by the author for clinical and numerical consistency. Final responsibility for interpretation rests with the author.An additional and important limitation specific to the VMI domain is the potential confounding effect of preschool attendance and literacy instruction. 

A significant body of research demonstrates that access to quality preschool accelerates cognitive and academic skill development, with effects that are particularly pronounced for children from low-income households (Magnuson & Duncan, 2016; Bailey et al., 2024). Preschool curricula in the four-year-old age range routinely incorporate letter recognition, alphabet knowledge, pre-writing activities, and structured fine motor practice, all of which directly engage the visual-motor and orthographic processing skills that O.T. Wizard’s VMI domain measures. Because O.T. Wizard does not currently collect data on whether a child is enrolled in preschool, how many days per week they attend, or what literacy instruction they are receiving, it is not possible to separate the contribution of preschool-based literacy exposure from the contribution of OT services to the VMI gains observed. The large VMI gains reported here almost certainly reflect the combined influence of OT intervention, natural maturation, and classroom-based literacy and pre-writing instruction. Future data collection that captures school enrollment status and attendance patterns would allow this important confounder to be examined directly.

Band G (n=6) and Band J (n=3) findings should be treated as exploratory only. The Participation and Executive Functioning longitudinal findings are subject to the novelty effect interpretation described above, which cannot be confirmed or ruled out without the prospective study design described in the continuing research section.

Continuing Research Needed

Rasch calibration remains the highest research priority for O.T. Wizard. Transforming ordinal raw scores into interval-level person measures will allow true scale-independent longitudinal comparison, validate the proportional scaling assumption underlying the natural growth correction, and identify items requiring revision. Current analyses are pre-Rasch and should be interpreted as preliminary clinical evidence rather than psychometrically standardized measurement. The O.T. Wizard National Try-Out Team initiative is designed to expand sample sizes needed for stable item calibration across all domains and age bands.

A typically developing comparison group would allow the 9.2% natural growth estimate to be validated empirically and replaced with domain-specific growth expectations calibrated against external developmental benchmarks. Recruiting a non-clinical sample, even a modest one, would strengthen the interpretive framework considerably and provide a more precise foundation for the gain-above-expected metric.

The novelty effect hypothesis for Participation and Executive Functioning requires prospective investigation. A study design capturing therapist-rated engagement and work habits at multiple time points within the first year of services, alongside parent-reported and teacher-reported measures, would allow empirical testing of whether first-evaluation ratings systematically overestimate authentic baseline functioning.

Longitudinal expansion with test-retest intervals of 12 to 24 months would allow examination of whether early VMI and ADL gains are sustained through kindergarten entry, and whether children who make the largest gains above natural growth in the preschool period show measurably better school readiness outcomes. Linking O.T. Wizard composite and domain scores to standardized criterion measures, including teacher-rated school readiness and kindergarten entry assessments, would establish predictive validity and position the platform’s data within the broader early childhood outcomes literature.

Conclusion

This analysis of 71 preschool-aged children with paired O.T. Wizard evaluations, examined through a transparent natural growth framework, extends the domain-level outcome picture established in the February 2026 report. Across a mean interval of 4.85 months and a natural growth expectation of 9.2%, five of eight assessed domains showed gains that were statistically significant, clinically large in effect, and substantially above what maturation alone would produce.

89% of children improved overall. 20 children crossed the 500-point composite functional threshold during the study interval. Visual Motor Integration showed gains of 21.1 points above the natural expectation, 614% above what developmental maturation alone would predict over the same period. Activities of Daily Living and Fine Motor Skills showed gains of 468% and 268% above expected, respectively. These are not marginal differences. They represent functional gains at rates that developmental maturation cannot explain.

These findings are preliminary. They require replication with larger samples, validated comparison conditions, and Rasch-calibrated measurement. What they establish is that structured domain-level digital assessment in pediatric OT can generate longitudinal outcome data that clearly and transparently distinguishes intervention-driven change from natural maturation. For a profession that has historically struggled to quantify its impact in terms that payers and educational systems recognize, that distinction is not a minor technical refinement. It is the foundation of evidence-based practice.

A six-part blog series examining what outcome data reveals about pediatric OT, what documentation systems currently miss, and how structured Response to Intervention measurement changes clinical practice is forthcoming in the O.T. Wizard Research Series beginning the week of March 9, 2026.

Disclosures

The author is the Founder and Clinical Architect of O.T. Wizard and has a financial interest in the platform. All analyses were conducted on de-identified clinical data collected in routine practice. Statistical analyses were generated with AI-based analytical tools and reviewed by the author for clinical accuracy and numerical consistency. Final responsibility for interpretation and reporting rests with the author. Data collection is ongoing. All data is de-identified in accordance with HIPAA regulations.

References

Daly, C. J., Kelley, G. T., & Krauss, A. (2003). Relationship between visual-motor integration and handwriting skills of children in kindergarten: A modified replication study. American Journal of Occupational Therapy, 57(4), 459-462. https://doi.org/10.5014/ajot.57.4.459

Duff, S. V., Chow, S. M., & Henderson, S. E. (2015). Developmental coordination disorder and its consequences for children. In A. F. Farrow & P. J. Tremblay (Eds.), Pediatric rehabilitation: Principles and practice (5th ed., pp. 189-215). Demos Medical Publishing.

Wick, S. S. (2026, February). O.T. intervention across nine functional domains in preschool children. O.T. Wizard Clinical Research Series. https://blog.otwizard.com/o-t-intervention-across-nine-functional-domains-in-preschool-children/

Zwicker, J. G., Missiuna, C., Harris, S. R., & Boyd, L. A. (2012). Developmental coordination disorder: A review and update. European Journal of Paediatric Neurology, 16(6), 573-581. https://doi.org/10.1016/j.ejpn.2012.05.003Bailey, D. H., Duncan, G. J., Cunha, F., Foorman, B. R., & Yeager, D. S. (2024). Persistence and fadeout of educational-intervention effects: Mechanisms and potential solutions. Psychological Science in the Public Interest, 21(2), 55-116.Gerde, H. K., Zhao, Y., Shu, L., & Gagne, J. R. (2025). Evidence-based instructional support for early writing in preschool and kindergarten: A scoping review. Reading and Writing. https://doi.org/10.1007/s11145-025-10751-8Magnuson, K., & Duncan, G. J. (2016). Can early childhood interventions decrease inequality of economic opportunity? RSF: The Russell Sage Foundation Journal of the Social Sciences, 2(2), 123-141.

About O.T. Wizard

O.T. Wizard is a clinical intelligence system for pediatric occupational therapy professionals. The platform evaluates performance in evaluations, forms, and daily treatment notes across twelve domains including visual-motor integration, fine motor skills, gross motor skills, praxis, visual perception, executive functioning, activities of daily living, and participation. O.T. Wizard is undergoing Rasch analysis validation to establish psychometrically sound, norm-referenced scoring with living norms that update continuously as the clinical database expands. For information about O.T. Wizard research or accessing the platform, visit otwizard.com.