Human Factor Validation of Pediatric Mobility Device: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Human Factor Validation of Pediatric Mobility Device (NCT03714256), a non-randomized na study. The primary outcome is Cumulative Number of Use Errors Associated With the Usage of the Device According to Labelling.

2. Clinical Question

This is a usability validation question, not a comparative treatment-effect question. The registry record names tasks involving charging and disconnecting the battery, adjusting seat and table height, adjusting speed, placing the child in the device, and adjusting the cushion and other support. The primary endpoint is the cumulative number of use errors identified in connection with device use according to the labelling. Although the record states the intended question and measurement approach, it does not report the observed error count or an analysis of that count. It therefore does not establish from the posted results how many errors occurred, how they were distributed across tasks or age groups, or how precisely any estimated quantity was measured.

3. Trial Design

The registry describes a completed study titled Human Factor Validation of Pediatric Mobility Device. It lists a planned and actual enrollment of 33, a start date of 2018-09-21, and a primary completion date of 2018-11-19. The study is classified as non-randomized, with no masking and a parallel model. Its phase is listed as NA. These labels describe the record’s design classification; they do not establish that a controlled comparison was performed.

There are two arms: Children 6-17 months and Children 18 - 36 months. Each arm description states that a parent/guardian and an occupational/physiological therapist performed usability activities with the pediatric mobility device according to instructions for use at a one time occasion. The device intervention is described as a powered patient mobility device. The matching arm descriptions indicate the same general device-use activity in both groups; the record does not describe a separate control intervention.

The trial is not randomized, and the registry explicitly cautions that the arms are not a like-for-like control comparison. Differences between the age groups, if any, cannot automatically be attributed to the device or to a treatment contrast. The record does not report a protocol-level explanation for the allocation approach, a sample-size justification, or other design details beyond those stated above. Those details should not be inferred from the enrollment, the two group labels, or the study’s validation purpose.

The registry lists one outcome measure, the cumulative number of use errors, but lists zero analyses. The posted record therefore sets out what the investigators intended to count without presenting an analyzed result for that endpoint. The design and outcome description can be explained, but the reported evidence cannot be used to quantify the observed usability result from this registry entry.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Cumulative Number of Use Errors Associated With the Usage of the Device According to Labelling, measured over One day.

The primary endpoint is the cumulative number of use errors associated with using the device according to its labelling. Its unit is errors, and the timeframe is one day. The endpoint description says that errors would be identified through observation and interview while users performed tasks involving the battery, seat and table height, speed, placing the child in the device, and adjusting the cushion and other support. The resulting summary count was intended to define the primary outcome.

A count endpoint can be useful in a human-factors evaluation because it represents the number of observed problems rather than a rating of overall satisfaction or a clinical outcome. In general, an error count can help identify where use-related difficulties arise, but the meaning of a count depends on what qualifies as an error, how observations are made, how repeated or related errors are handled, and how completely the planned activities are captured. The registry record does not give operational definitions or additional counting rules beyond its brief description.

The posted record does not report the observed count, a count distribution, or a breakdown by task or age group. Nor does it report an estimate of uncertainty around the endpoint. The description identifies the intended measure; it is not itself evidence of a particular number of errors or of a particular pattern of usability.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry labels this study non-randomized, unmasked, and parallel. It lists two age-group arms and describes device-use activities in each. These are design descriptions, not statistical analyses. The record does not report a statistical analysis plan, a model for the error count, an interim analysis, or a sample-size justification. It lists zero analyses. Statistical methods that might be considered for this kind of outcome should therefore be understood as general concepts, not as methods known to have been used.

What does a count outcome represent?

The primary endpoint is a number of errors. In general, count data record how often an event occurs within a defined observation period or set of opportunities. The count has meaning only in relation to the process used to identify events and to the activities over which they are counted. Here, the stated timeframe is one day, and the listed tasks give context for observation. The registry does not report the actual count or specify additional rules for distinguishing an error from a non-error, handling repeated occurrences, or assigning errors to particular tasks.

In general, a count may be summarized with a total, a distribution, or a rate when the relevant exposure or opportunity is defined. These summaries answer different questions. A total describes the number of recorded events; a distribution describes how counts vary among observed units; and a rate relates events to an exposure measure. The registry states a cumulative number as the primary outcome but does not report a rate, an exposure denominator for such a rate, or a distribution of counts. It would not be appropriate to assume that any of these summaries was calculated.

Why can count data need special care?

In general, count observations may be more variable than a simple statistical model expects. Over-dispersion means that variation in the observed counts exceeds what a model assumes. If over-dispersion is present and ignored, standard errors and confidence intervals from an unsuitable model can be misleading. This is a general consideration for count outcomes; the registry does not report whether over-dispersion was assessed or which model, if any, was used. Since no analysis is posted, there are no model assumptions or diagnostics to evaluate for this study.

Another general issue is that counts can have many zero values or a small number of larger values. The appropriate summary or model depends on the data pattern and the study question. A reader cannot select among methods based only on the endpoint label. The record gives neither the count distribution nor an error-level dataset, and it does not report whether counts were summarized per participant, task, or another unit. The description says the summary of identified errors defines the primary outcome, but does not add those analytic details.

What would an estimate and interval tell a reader?

In general, an estimate describes a result in the observed data, while a confidence interval describes the statistical uncertainty around that estimate under the assumptions of the method used. An interval is not a guarantee that the true value lies within its bounds, and its interpretation depends on the analysis and data collection. This record reports no estimate or confidence interval for the primary endpoint. Thus, readers cannot use interval width to judge precision, nor can they evaluate whether the result is compatible with a range of plausible values.

Similarly, a p-value would be relevant only in the context of a specified statistical question and analysis. It does not measure the size or importance of an effect. No p-value or tested hypothesis for the error-count endpoint is reported. It would be inaccurate to infer statistical significance or non-significance from the study’s completion status, enrollment, or outcome description.

What do the design labels imply for comparisons?

In general, random allocation can help make groups comparable for a treatment contrast by distributing measured and unmeasured characteristics across groups. This study is explicitly classified as non-randomized, and the registry cautions against treating its arms as a like-for-like control comparison. The age-group arms are described as having the same device-use activity, not as device and control conditions. A statistical comparison of their outcomes, if one were reported, would need to be interpreted with care; the registry does not report such an analysis.

The absence of masking is also a design label, not a result. In general, knowledge of the activity being assessed can affect how observations are made or interpreted, depending on the procedures used. The record does not explain any safeguards for observation or interview, so no particular safeguard should be assumed. Nor does it report assessor agreement or an evaluation of measurement consistency.

How should planning illustrations be read?

In general, a sample-size calculation describes a planned study scenario under stated assumptions. It is not a summary of what the observed data show, and a calculation based on an observed effect is not observed power. The planning assumptions noted for this page describe an illustration using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; they also describe the effect to detect as a stated fraction of an observed effect. The registry record does not report the trial’s own sample-size justification. Because the primary analysis and observed effect are not reported, any such illustration should not be treated as a result of this validation study.

In this record, the most important statistical fact is not a choice among models but the absence of a posted endpoint analysis. General statistical concepts can explain what would matter when analyzing error counts, but they cannot reconstruct the missing data or establish which procedure the investigators used. The registry record does not report an analysis plan, a fitted model, a precision estimate, or a conclusion based on the primary outcome.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists one outcome measure and zero analyses. It does not report whether the investigators prespecified additional endpoints outside the listed registry outcome, conducted exploratory analyses, or adjusted for multiple testing. A multiplicity procedure is therefore not reported in the registry record. With no posted analysis results, there is no set of reported hypothesis tests whose multiplicity can be evaluated.

Missing-data methods and analysis populations are also not reported in the registry record. The entry does not say how incomplete observations, missed tasks, or participants without an evaluable endpoint would be handled. It does not identify an intention-to-treat, per-protocol, or other analysis population. The listed enrollment is not, by itself, evidence that every enrolled participant contributed complete data to the primary outcome.

These absences matter because an endpoint based on observed tasks can be affected by which activities were completed and which observations were available. In general, excluding incomplete observations or using different assumptions about missing outcomes can change an estimate. That is a general methodological point, not a claim that missing observations occurred in this study. The record does not report whether any such observations occurred, how completeness was assessed, or what rules were applied.

The registry’s concise result entry should therefore be read as incomplete for statistical assessment of the primary outcome. It does not permit a reader to check prespecification, selective reporting, missingness, or the analysis set. These limitations are distinct from the non-randomized design: even a descriptive count would require enough information about the observed data and analysis population to understand what it represents.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The registry’s adverse-event groups list Children 6-17 Months with 14 at risk and 0 affected by serious adverse events; the entry also lists 14 at risk and 0 affected by other adverse events, with 0 deaths. For Children 18 - 36 Months, it lists 19 at risk and 0 affected by serious adverse events; it also lists 19 at risk and 0 affected by other adverse events, with 0 deaths. No serious adverse-event terms are listed.

These figures mean that the registry reports zero affected participants for the listed serious and other adverse-event categories in each group, and zero deaths. They should not be expanded into a claim that no event of any kind occurred outside the categories or reporting process represented in the record. The entry does not give further detail about event definitions, ascertainment procedures, follow-up beyond the stated study activities, or completeness of event collection.

Safety-event counts do not answer the primary usability question. The primary endpoint was a count of use errors during device tasks, while the adverse-event figures are separate entries. Zero reported adverse events do not reveal the number or nature of use errors, and the absent error-count analysis cannot be filled in from the safety table. These observations describe what the registry reports, not a complete assessment of safety or usability.

12. What the Result Does, and Does Not, Mean

This registry entry documents a completed human-factors validation study of a pediatric powered mobility device. It describes two age groups, a one-time usability activity with a parent/guardian and an occupational/physiological therapist, and a primary outcome intended to count use errors observed through task performance, observation, and interview. These details explain the study’s purpose and the kind of information it sought to collect.

The posted record does not report the primary error count or an analysis of that outcome. As a result, it does not show how many errors were observed, whether errors differed by task or age group, or how precise an estimate would be. It cannot support a quantitative conclusion about the endpoint based on the registry entry alone. The fact that the study is marked completed does not supply the missing result.

The two arms should not be interpreted as a randomized device-versus-control comparison. They are age groups in a non-randomized study, and both arm descriptions refer to use of the device according to instructions. The registry explicitly warns that the arms are not a like-for-like control comparison. Any hypothetical difference between them would not by itself establish a causal explanation.

In general, a human-factors validation can provide information about usability when tasks and observations are clearly defined and results are reported in enough detail to assess what happened. Here, the task list and intended measurement approach are described, but the registry does not include the resulting count or detail about error definitions and analysis procedures. The record also reports zero affected participants for the listed adverse-event categories, but those figures are not the primary usability result.

The responsible interpretation is therefore limited: the record specifies a usability question and reports study-design and adverse-event information, but it does not report the result needed to answer the primary question. It neither establishes a favorable nor an unfavorable usability finding from the posted endpoint data. Readers should distinguish the stated purpose of validation from the statistical evidence actually available in this registry entry.

13. Why This Trial Matters Statistically

This study is statistically interesting because its primary outcome is an error count arising from use of a device, rather than a conventional comparison of clinical outcomes between randomized treatment groups. The measurement process is central: the count depends on what is considered a use error, which tasks are observed, and how observations and interviews contribute to the final summary. The registry names several tasks and identifies the intended count, giving readers a starting point for understanding the measurement target.

The design also illustrates why a parallel-arm label does not necessarily indicate a controlled comparison. Here, the groups are separated by age and receive descriptions of the same device-use activity. Allocation is non-randomized, and the registry explicitly cautions that the arms are not like-for-like controls. Statistical interpretation must follow the actual design rather than the appearance of two arms.

It also highlights the difference between registering an endpoint and reporting its result. A clearly named outcome does not let readers assess its magnitude or precision when the observed count and analysis are absent. The registry lists one outcome measure but zero analyses. This makes reporting completeness a central issue: the study’s question can be described, but the result cannot be evaluated from the posted analysis record.

Finally, the entry separates usability outcomes from adverse-event reporting. The adverse-event groups report no affected participants in the listed categories, but those figures do not substitute for the primary error count. Taken together, the record is a useful example of how design labels, endpoint definitions, analysis reporting, and safety entries answer different statistical questions. It also shows why careful readers should avoid drawing a conclusion that the posted results do not contain.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

Several limitations specific to this registry entry restrict interpretation. Most importantly, although the primary endpoint is described, the cumulative number of use errors is not reported, and the registry lists zero analyses. There is no posted endpoint estimate, breakdown by age group or task, or measure of statistical precision. This prevents readers from assessing the primary result from this record.

The endpoint description is brief. It names the tasks and says errors were captured through observation and interview, but the registry does not report a detailed operational definition of an error, rules for repeated or related errors, or how observations and interviews were combined. It also does not report whether assessment consistency was checked. These omissions make it difficult to assess the reproducibility and interpretation of the intended count.

The study is non-randomized, unmasked, and divided into age-group arms. The registry says the arms are not a like-for-like control comparison. Accordingly, the design does not support treating the groups as device and control conditions. The record does not report further design details that would justify a stronger comparative interpretation.

The registry does not report the analysis plan, sample-size justification, missing-data approach, analysis population, or multiplicity procedures. It also does not report whether all planned tasks were completed or whether all participants contributed endpoint data. These are absences in the registry record, not evidence that any particular problem occurred. Finally, the adverse-event figures have limited accompanying detail, so they should be read as the reported entries rather than as a comprehensive account of all possible safety events.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Human Factor Validation of Pediatric Mobility Device — NCT03714256.
• Registry record last updated 2021-01-14; status last verified 2021-01.
• Results first posted 2021-01-14.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

The registry describes a completed, non-randomized, unmasked, parallel usability validation study of a powered pediatric mobility device. It lists 33 participants and two age-group arms: Children 6-17 months and Children 18 - 36 months. Both arm descriptions involve a parent/guardian and an occupational/physiological therapist performing device-use tasks according to instructions for use at a one time occasion.

The primary outcome is the cumulative number of use errors associated with use according to labelling, captured through observation and interview during a set of specified tasks. The registry lists one outcome measure but zero analyses. The observed error count and its statistical precision are not reported in the registry record.

The arms are not a randomized or like-for-like control comparison. The adverse-event entries list zero affected participants for serious and other adverse events in both groups, and zero deaths. These entries do not provide the missing primary usability result.