This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for AR Projections for Eye-gaze Evaluation in Phantoms (NCT07161024), a na na study. The primary outcome is Stone Count.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT07161024 |
| Phase | NA |
| Condition | Kidney Stones |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 8 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Vanderbilt University Medical Center |
| Results posted | Yes |
2. Clinical Question
Population
Users performing a kidney-stone identification task in phantoms. The registry record lists an enrollment of 8, but does not report participant characteristics, experience levels, or how participants were recruited.
Intervention
Augmented-reality markers used during the phantom task. Each user performs the task with each of three markers.
Comparator
The task performed without a marker is the within-task reference condition. The record does not describe a separate control group, and the registered allocation is listed as NA.
Primary question
How does the percentage of stones seen or found during the phantom task vary across the marker conditions and the no-marker condition? Outcome estimates are not reported in the registry record, so the posted information does not answer this question quantitatively.
The study concerns visualization during a simulated endoscopic kidney-stone task, rather than treatment outcomes in patients. Its stated project aim is to develop an augmented-reality tool intended to support skill acquisition. The registry background describes limited visualization as a challenge in endoscopic stone surgery and identifies surgeon experience as relevant to seeing the collecting system. The registered task evaluates stone identification in phantoms, not residual fragments, recurrence, complications, or patient recovery.
The question is therefore best read as a task-performance question: whether stone visibility differs across marker conditions within this testing setup. The record says the phantom and marker ordering is randomized to reduce learning effects. That ordering feature does not make the study a randomized comparison between separate treatment groups. Because no primary outcome results or analyses are reported, it is not possible to describe the direction, size, or precision of any difference.
3. Trial Design
The registry lists this study as completed, with a single-group model, allocation recorded as NA, and no masking. The listed enrollment is 8. The recorded start date is 2024-10-14, and the primary completion date is 2025-02-05. The phase is listed as NA. Vanderbilt University Medical Center is named as the sponsor.
The registered arm is called AR Marker Test. Its description says each user performs a kidney-stone identification task in phantoms with each of three augmented-reality markers and without any marker. It also says the phantom and marker ordering is randomized to reduce learning effect. This indicates repeated task conditions for users within the described setup; it does not indicate separate, parallel groups receiving different interventions. The registry explicitly lists the study among records that are not a randomized comparison, so the conditions should not be read as a like-for-like control-arm trial.
The listed intervention is a device called Augmented reality. The primary outcome is Stone Count, with a percentage unit, a mean parameter, and standard deviation as the dispersion measure. Its timeframe is 1-10 min. The stated population for the measure is the percentage of stones found, and its description refers to percentages of stones seen. Secondary outcomes are Gaze Metrics, Completion Time, and NASA Task Load Index.
The registry record does not report further design details such as the exact task protocol, participant eligibility criteria, number or location of stones in each phantom, marker specifications, or the sequence-generation procedure. It also does not report a protocol or statistical analysis plan. Those omissions limit how fully the testing conditions and analysis decisions can be assessed.
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.
Before assignment: No significant events occurred between enrollment and assignment of each group.
Overall Study
| Stage | Enrolled Residents and Experts, Eye Gaze Metrics |
|---|---|
| STARTED | 8 |
| COMPLETED | 8 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: percentage of stones found.
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.
Population: all participants we enrolled.
| Characteristic | Unit | AR Marker Test |
|---|---|---|
| Participants analysed | 8 | |
| Age, Continuous | years | 32 (30 to 35) |
| Sex: Female, Male: Female | Participants | 4 |
| Sex: Female, Male: Male | Participants | 4 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 3 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 2 |
| Race (NIH/OMB): White | Participants | 2 |
| Race (NIH/OMB): More than one race | Participants | 1 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Region of Enrollment: United States | Participants | 8 |
| eye gaze metrics, area of interest | cm2 | 1295 (SD 448) |
6. Primary Endpoint
The registry lists the primary outcome as Stone Count, measured over 1-10 min.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | percentage |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is titled Stone Count and is expressed as a percentage. The registry describes it as the percentage of stones seen and identifies the measured population as the percentage of stones found. In this setting, the measure is intended to represent how much of the stone content is identified during a phantom task. The listed timeframe is 1-10 min, and the planned summary is a mean with standard deviation.
Using a percentage can make a task measure interpretable in relation to the stones available for identification, rather than reporting only a raw count. In general, measures of visual identification can help describe performance on a task that focuses on visualization. This is a general explanation of the measure’s possible statistical role, not a finding about this study.
The registry description also includes a passage about NASA Task Load Index (NASA-TLX), including its dimensions and scoring. NASA-TLX is separately listed among the secondary outcomes. The record does not clarify why that material appears in the primary endpoint description, or whether it is intended to qualify the Stone Count measure. The endpoint title, unit, and population point to stone visibility or identification, but the wording leaves some ambiguity about how the primary measure was operationalized.
No primary endpoint values, group or condition summaries, or analysis results are reported in the registry record. Consequently, the endpoint’s observed mean, variability, and differences across task conditions cannot be described from the posted results.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record provides the study’s design and outcome labels, but it does not report numerical results for Stone Count or the secondary outcomes. It also lists 0 analyses. There is therefore no posted estimate of the percentage of stones seen or found under any condition, and no statistical comparison to interpret. The record cannot establish whether visibility was higher, lower, or similar with any marker relative to the no-marker condition.
The primary measure is described as a mean with standard deviation. In general, a mean describes the average value in a set of observations, while a standard deviation describes how dispersed observations are around that mean. Neither summary is reported for this outcome. There are also no confidence intervals or test results in the registry record. In general, a confidence interval expresses the precision of an estimate across values compatible with the data and method; without an estimate and its interval, the precision of an effect cannot be assessed.
The design description says each user undertakes the task with three markers and without a marker, with ordering randomized to reduce learning effects. Those are repeated conditions in a task, not independent parallel groups. In general, analyses of repeated observations need to account for the fact that measurements from the same user may be related. The registry record does not report whether or how such within-user dependence was handled. No method for comparing the conditions is listed.
The no-marker task can serve as a reference condition for describing performance, but the record does not identify it as a separate randomized control arm. The registry’s design fields and its explicit note that this is not a randomized comparison argue against interpreting the marker conditions as a conventional treatment-versus-control trial. The posted information also does not describe allocation concealment, masking, or an independent assessor; masking is listed as NONE.
No conclusion about the magnitude or precision of an association between marker condition and stone identification can be drawn from the available result fields. This absence of reported estimates is not evidence that the conditions produced the same performance, nor evidence that a marker improved or impaired performance. It means the registry record does not provide the outcomes needed to make that statistical assessment.
The registry background gives a clinical rationale involving visualization and surgical training, but the endpoint is a phantom identification task. Statistical interpretation should stay within that setting. Even if task results were available, they would describe performance in this study setup; the record does not establish how such performance relates to surgical skill, patient outcomes, or subsequent clinical practice.
9. Statistical Methods Explained
What design is described?
The study is registered as a single-group evaluation with allocation listed as NA and masking listed as NONE. The arm description says each user performs the phantom task with each of three augmented-reality markers and without a marker. The ordering of phantoms and markers is randomized to reduce learning effect. In general, varying task order can help address systematic changes in performance that occur as participants become familiar with a task. The record does not give the order-generation method or explain how the ordering was implemented.
Because the conditions are described as repeated tasks by each user, the resulting measurements may be correlated within users. In general, treating correlated measurements as if they came from unrelated people can misstate uncertainty. Analyses of repeated conditions often use methods that account for within-person variation, but the registry record does not report which, if any, method was used. It reports 0 analyses, so there are no posted analysis specifications or outcome tests to evaluate.
What does the endpoint summary mean?
The primary outcome is identified as a continuous measure summarized by a mean and standard deviation. In general, the mean describes the central average, and the standard deviation conveys the spread of observed measurements. A percentage of stones seen or found is the stated outcome concept. The registry record does not specify the denominator used to form that percentage, how partially seen stones were handled, or how multiple task observations were combined. It also does not report the observed means or standard deviations.
The endpoint description includes a NASA-TLX passage. NASA-TLX is separately listed as a secondary outcome and is described as assessing subjective workload across mental demand, physical demand, temporal demand, performance, effort, and frustration. Each dimension is rated from 0 to 100, with higher scores indicating greater perceived workload; the overall index is the average of the dimension scores and ranges from 0 to 100. These details describe the workload instrument, not the primary Stone Count endpoint. The registry record does not clarify the placement of the NASA-TLX wording in the primary outcome description.
How should uncertainty be understood?
General statistical explanation: an estimate gives a best summary of an observed effect under a specified method, while a confidence interval communicates its uncertainty. A narrow interval generally indicates greater precision than a wide interval, though precision does not by itself establish practical importance or eliminate bias. No primary estimate, confidence interval, or test result is reported in the registry record, so neither effect size nor precision can be evaluated.
General statistical explanation: standard deviations describe variation among observations, whereas standard errors describe uncertainty in an estimated quantity. They are not interchangeable. The registered dispersion measure is standard deviation, but no numerical dispersion is posted. The record does not report whether any adjusted or unadjusted estimates were planned or calculated.
What do the planning illustrations represent?
The sample-size assumptions describe planning illustrations based on a stated fraction of an observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. For time-to-event settings, the stated planning convention is total events; other settings use participants per arm. These are planning illustrations, not observed power. They do not establish what the trial was designed to detect, and the registry record does not report the trial’s own sample-size justification. Since this is a single-group task with repeated conditions rather than a randomized two-arm comparison, assumptions framed around equal allocation between two arms should not be mistaken for the study’s registered design.
In general, a planning calculation asks what sample size might be needed under specified assumptions. It is not a measure of the probability that a completed study has detected an effect, and it cannot substitute for reporting observed estimates and their uncertainty. No values for the planning illustrations are discussed in this narrative, and no observed outcome estimate is available in the registry record for an independent assessment of the assumptions.
What is not specified?
The registry record does not report a statistical analysis plan, the method for comparing repeated conditions, a treatment of missing observations, the analysis population, or a multiplicity strategy. It does not describe whether any interim analyses occurred. It also does not provide detail on model assumptions, covariate adjustment, or handling of outlying task measurements. These are distinct elements of a statistical plan; the available record does not support assumptions about how they were addressed.
General explanation: over-dispersion occurs when observed variability exceeds what a chosen statistical model expects. If present, it can make standard errors and tests from a too-restrictive model unreliable. Whether over-dispersion is relevant depends on the data type and model; the registry does not provide an analysis model or outcome data from which to assess it. No claim about over-dispersion, distributional fit, or model adequacy can therefore be made for this study.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists one primary outcome, Stone Count, and three secondary outcomes: Gaze Metrics, Completion Time, and NASA Task Load Index. It also reports 5 outcome measures and 0 analyses. The record does not explain how the listed outcomes relate to the count of outcome measures, or whether any outcome was subdivided into multiple measures or time points.
Multiplicity arises in general when several outcomes, conditions, or comparisons are tested: the chance of finding at least one apparently notable result can increase when many tests are considered. Study plans may address this through a prespecified primary comparison, adjustment methods, or an explicitly exploratory interpretation. The registry record does not report a multiplicity strategy, a hierarchy among comparisons, or which comparisons were intended to be confirmatory. No test results are posted, so the consequences of any unreported multiplicity handling cannot be assessed.
Missing-data methods and analysis populations are also not reported in the registry record. There is no description of how incomplete task observations, unusable recordings, or absent outcome measurements would be handled. The record does not define an intention-to-treat, per-protocol, or other analysis population. It would be inappropriate to infer that all enrolled participants contributed to every outcome simply from the enrollment field.
General explanation: missingness can affect an estimate when the likelihood of an observation being unavailable is related to the outcome or study condition. The appropriate method depends on why data are missing and on the analysis objective. No missing-data assumptions or methods can be evaluated without those details and the outcome data. The record also does not report interim analyses or stopping rules, so no conclusions about their use are warranted.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| AR Marker Test | 0 | 8 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| AR Marker Test | 0 of 8 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 1% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| AR Marker Test | 0 of 8 |
The posted safety fields list the AR Marker Test group with 8 at risk for serious adverse events and 0 serious adverse events. The same group lists 8 at risk for other adverse events and 0 other adverse events, with 0 deaths. No top serious adverse-event terms are listed.
These counts describe what is recorded in the registry safety fields; they do not demonstrate that the task or device has no safety risks. The record does not explain how adverse events were defined, collected, monitored, or attributed, or provide additional details about the observation period. Nor does it report a separate safety analysis. The zero counts should therefore be read as no events recorded in these fields, rather than proof that no event could occur.
The task is described as a phantom evaluation, and the safety figures are not patient treatment outcomes. No comparison of safety between separate randomized groups is available. The single-group design and absence of a comparator mean these counts cannot estimate a relative safety effect. The registry record does not report further safety context or event narratives.
12. What the Result Does, and Does Not, Mean
The registry record describes a completed evaluation of augmented-reality markers during a kidney-stone identification task in phantoms. It establishes the general testing setup, the primary endpoint label, the stated secondary outcomes, and some registry-level safety counts. It does not report numerical outcome results or statistical analyses. As a result, there is no basis in the posted results to quantify stone visibility, gaze behavior, completion time, or workload across conditions.
The primary question concerns a task-level measure: the percentage of stones seen or found with markers and without a marker. That is narrower than demonstrating a change in surgical skill. The study description does not report clinical procedures, patient outcomes, residual fragments, repeat surgery, or complications as measured endpoints. The project’s stated training rationale supplies context but is not itself evidence of a measured training benefit.
The within-task structure may allow performance to be described across marker conditions for the users who completed the tasks. In general, repeated conditions can provide useful comparisons within participants, but the statistical interpretation depends on how observations are analyzed and how order effects and within-person dependence are handled. The registry record does not report the analysis method, and it does not provide results needed to assess those issues.
The absence of reported outcome estimates should not be interpreted as a null result. It also does not support a claim that a marker improves visualization. It means the registry record does not contain the findings needed to judge the direction, magnitude, or precision of the task-performance results. The stated serious adverse-event and other adverse-event counts are similarly limited to the posted safety fields and do not establish general safety.
Any implications for surgeon training or patient care would require evidence beyond the task description, including reported outcome data and an assessment of how phantom performance relates to real-world practice. The record does not provide that evidence or a basis for drawing clinical conclusions.
13. Why This Trial Matters Statistically
This study illustrates why trial design and outcome reporting need to be read together. A registered study can describe an intervention, endpoint, enrollment, and task conditions while still lacking the outcome estimates needed to answer its research question. Here, the record identifies stone visibility as the primary measure and describes repeated marker conditions, but provides no outcome analyses. Design details alone cannot show whether performance differed.
The record also highlights the distinction between a single-group task evaluation and a randomized comparison between separate groups. The task description includes a no-marker condition and randomized ordering, but those features do not turn the setup into a parallel-arm trial. Recognizing the within-user structure matters because repeated observations may be related, and statistical methods should reflect that structure. The analysis method is not reported.
Another statistical issue is endpoint definition. The primary outcome title and unit refer to a percentage of stones seen or found, while the description also contains NASA-TLX material that is separately listed as a secondary outcome. Clear endpoint definitions help readers identify the intended measurement, denominator, and analysis. The registry record leaves some of those details unspecified.
Finally, a registry entry can list planning assumptions without reporting observed findings. Planning illustrations answer a design question under specified assumptions; they are not observed power and are not a substitute for effect estimates and uncertainty. In this record, no analyses or outcome estimates are reported, so readers cannot connect planning assumptions to observed task performance. These distinctions are relevant when assessing what a completed study can—and cannot—contribute statistically.
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.
The main limitation for interpretation is that the registry record does not report numerical results for the primary or secondary outcomes and lists 0 analyses. This prevents assessment of effect direction, magnitude, variability, and precision. The completed status does not fill that reporting gap.
The design is described as single-group, with repeated marker and no-marker task conditions. The record does not provide enough detail to assess how within-user dependence was handled or whether order effects were addressed in the analysis. Randomized ordering is described as a way to reduce learning effect, but the procedure and its implementation are not reported. Masking is listed as NONE.
The endpoint definition is not fully clear. Stone Count is expressed as a percentage, and the population description refers to the percentage of stones found. However, the primary outcome description also contains NASA-TLX text, while NASA-TLX is listed as a secondary outcome. The denominator and scoring details for the primary percentage are not reported.
The record does not report participant characteristics, eligibility criteria, recruitment details, phantom specifications, marker descriptions, missing-data handling, analysis populations, multiplicity procedures, or a statistical analysis plan. It also does not report a sample-size justification for the study itself. These omissions restrict evaluation of reproducibility, potential bias, and the applicability of task findings beyond the phantom setup. The background rationale does not supply evidence of clinical effects, and no patient outcomes are listed among the reported results.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: AR Projections for Eye-gaze Evaluation in Phantoms — NCT07161024.
- Registry record last updated 2026-04-20; status last verified 2026-04.
- Results first posted 2026-04-20.
- 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.
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18. Record Summary
The registry record describes NCT07161024, AR Projections for Eye-gaze Evaluation in Phantoms, sponsored by Vanderbilt University Medical Center. The study is listed as completed, with a single-group model, allocation NA, masking NONE, and enrollment of 8. Its recorded start date is 2024-10-14, and its primary completion date is 2025-02-05.
The AR Marker Test arm describes a kidney-stone identification task in phantoms using each of three augmented-reality markers and no marker, with ordering randomized to reduce learning effect. Stone Count is the primary outcome, expressed as a percentage and summarized by a mean and standard deviation; its timeframe is 1-10 min. Gaze Metrics, Completion Time, and NASA Task Load Index are listed as secondary outcomes.
The record lists 5 outcome measures and 0 analyses. Outcome estimates and statistical comparisons are not reported in the registry record. Safety fields report 0 serious adverse events, 0 other adverse events, and 0 deaths for the listed group.