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 The Effects of Lower Right Limb Orthopedic Immobilization on Driving Performance (NCT00950729), a randomized na study. The primary outcome is Mean Breaking Time Measured on a Driving Car Simulator.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00950729 |
| Phase | NA |
| Condition | Walking Cast Right Leg Immobilisation Effects, Aircast Right Leg Immobilisation Effects |
| Allocation | Randomized |
| Design model | Crossover |
| Masking | None (open label) |
| Enrollment | 48 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Université de Sherbrooke |
| Results posted | Yes |
2. Clinical Question
Population
Healthy volunteers. The registry record lists 48 participants enrolled and identifies the safety group as healthy subjects. It does not report further eligibility details or describe a separate analysis population for the primary endpoint.
Intervention
Driving with a plaster cast or an Aircast walker immobilizing the lower right limb. The registry also names the cast condition as a walking cast in its description of the study.
Comparator
Driving while wearing running shoes, which serves as the unimmobilized comparison condition. The registry describes testing all participants under the shoe and immobilization conditions.
Primary question
How do lower right limb immobilization conditions relate to braking performance during simulated emergency braking, including braking with and without a distracter? The primary endpoint is titled mean breaking time, measured in seconds.
The study addresses a performance question in a controlled simulator setting. The stated background is that effects of lower right limb orthopedic immobilization on driving performance were unknown, and the objective was to evaluate immobilization effects on braking performance under simulated driving conditions. The reported setting is healthy volunteers rather than a population described as needing immobilization for an injury or procedure.
The registry record identifies a randomized crossover design, so the intended comparisons concern performance across conditions within a study organized around repeated condition exposure. It does not report the randomization sequence, the order in which conditions were experienced, or the interval between them. Nor does it report numerical braking results, estimates of the differences between conditions, or uncertainty measures. Consequently, the clinical question can be described from the planned conditions and endpoint, but the magnitude and precision of any observed condition differences cannot be assessed from the registry record.
3. Trial Design
The registry record describes a completed, randomized, unmasked crossover experiment involving 48 healthy volunteers. It lists three driving conditions: running shoes, a plaster cast, and an Aircast. Its study summary describes the cast and Aircast as two types of orthopedic immobilization of the lower right limb, compared with running shoes. The design is classified as crossover, but the record does not explain the assignment sequence, condition order, or whether any washout interval was used.
The study used a computerized driving simulator. Participants were evaluated during emergency braking with and without a distracter. The summary says the simulator measured maximum force applied to the brake pedal, braking reaction time, and total braking time. The registry lists two outcome measures, but it does not provide a complete outcome-by-condition results set or explain how the listed measures map to the outcome count.
Recruitment began in 2007-03, and primary completion is recorded as 2007-06. The primary outcome timeframe is stated as June 2007 to September 2007. These entries describe different registry dates, but the record does not explain their relationship. The study status is completed. The phase is listed as NA, which is consistent with the record describing an experimental study in healthy volunteers rather than a drug development phase.
Masking is listed as none. Further details on who knew condition assignment, how randomization was implemented, and how simulator measurements were collected or processed are not reported in the registry record. The record also does not report a protocol, a sample-size justification for the original trial, or the planned statistical model. These omissions limit how fully the experimental design and analysis can be reconstructed from the registry entry alone.
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.
Driving With Running Shoes
| Stage | Healthy Subjects |
|---|---|
| STARTED | 48 |
| COMPLETED | 48 |
| NOT COMPLETED | 0 |
Driving With Plaster Cast
| Stage | Healthy Subjects |
|---|---|
| STARTED | 48 |
| COMPLETED | 48 |
| NOT COMPLETED | 0 |
Driving With Aircast
| Stage | Healthy Subjects |
|---|---|
| STARTED | 48 |
| COMPLETED | 48 |
| NOT COMPLETED | 0 |
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.
| Characteristic | Unit | Healthy Subjects |
|---|---|---|
| Participants analysed | 48 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 48 |
| Age, Categorical: >=65 years | Participants | 0 |
| Age, Continuous | years | 42.27 (SD 10.06) |
| Sex: Female, Male: Female | Participants | 24 |
| Sex: Female, Male: Male | Participants | 24 |
| Region of Enrollment: Canada | participants | 48 |
6. Primary Endpoint
The registry lists the primary outcome as Mean Breaking Time Measured on a Driving Car Simulator, measured over June 2007 to September 2007.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | seconds |
| Endpoint classification | Continuous Endpoint |
The recorded primary endpoint is titled mean breaking time measured on a driving car simulator, with seconds as its unit. Its description says the simulator measured braking reaction time and total braking time during emergency braking, both with and without a distracter. The study summary also describes maximum force applied to the brake pedal as a measured performance feature. The record does not clarify whether the primary mean breaking time refers specifically to reaction time, total braking time, or a differently defined measure. That distinction matters because these quantities represent different stages or aspects of a braking response.
In general, a time-based endpoint is used to quantify how long a response takes under the tested conditions. Recording performance in a simulator permits a controlled comparison of driving tasks and conditions without relying only on subjective impressions. Including trials with and without a distracter can assess performance in more than one simulator context, but the registry does not describe the distracter or report condition-specific results for either context.
The endpoint is specified as a mean, with standard deviation as the stated measure of dispersion. A mean describes the central value of measurements, while a standard deviation describes their spread around that mean. Neither endpoint values nor standard deviations are reported in the registry record. The meaning of the outcome can therefore be explained, but its observed level, variability, and precision cannot be evaluated from this record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record establishes the study question, conditions, setting, and primary endpoint, but it does not provide the numerical results needed to judge the observed braking performance. It reports no mean breaking-time values by condition, no standard deviations, no contrasts between conditions, and no confidence intervals or p-values. It is therefore not possible to state from this record whether the cast or Aircast condition was associated with a longer or shorter time than driving in running shoes, or how large or precise any such difference may have been.
The reported crossover design is relevant to interpretation because observations across conditions may be related when they come from the same volunteer. In general, a within-person comparison can account for stable differences between people, but an appropriate analysis must also consider the repeated condition structure. The registry record does not report whether the posted analysis used paired comparisons, a repeated-measures model, or another method. It also does not provide the condition sequence or period information needed to assess potential order effects.
The endpoint description combines terms for braking reaction time and total braking time, while the primary outcome title refers more generally to mean breaking time. Without operational definitions or posted results, the exact quantity summarized as the primary endpoint remains unclear. The study summary reports that measurements were taken with and without a distracter, but the registry does not show whether these settings were analyzed separately, combined, or treated as secondary questions.
The record lists 48 enrolled participants. That enrollment figure alone does not establish how many contributed usable primary-outcome measurements, whether all participants completed every condition, or whether any observations were excluded. The primary endpoint population is not specified. The record lists zero analyses, so there is no analysis set, model output, or documented inferential comparison to interpret.
The record’s absence of posted estimates should not be read as evidence of equal performance across conditions, nor as evidence of a difference. It means the magnitude, direction, and uncertainty of the outcome are not reported in the registry record. Any conclusions about effects on braking performance would require outcome data and an adequately described analysis, neither of which appears in this entry. The simulator setting also defines the scope of what was studied: results, if available elsewhere, would concern performance in the described simulated task, and the registry record does not establish how such measurements correspond to driving outside the simulator.
9. Statistical Methods Explained
Statistical interpretation depends on both the design and the reported outcome information. The registry classifies this experiment as randomized and crossover, and it defines a continuous primary outcome summarized as a mean with standard deviation. It does not report the statistical analysis method or numerical outcome results. The explanations below describe general statistical concepts relevant to this design; they are not claims about analyses actually conducted for this trial.
What does the mean describe?
A mean is a measure of the central level of a set of observations. For a time endpoint, it would summarize the average recorded time under a specified condition and simulator context. A mean by itself does not describe how similar participants’ measurements were. The standard deviation provides a measure of dispersion: a larger standard deviation indicates greater spread around the mean, while a smaller one indicates that observations are more concentrated. The registry names standard deviation as the dispersion measure but does not report its values.
For meaningful comparisons, the endpoint definition must be consistent across conditions. The record’s primary outcome title refers to mean breaking time, while the description mentions braking reaction time and total braking time. These are not interchangeable labels unless the measurement definitions show that they refer to the same calculated quantity. The registry does not provide that clarification. It also does not state whether measurements with and without a distracter were treated as separate endpoint contexts or combined.
Why does the crossover design matter?
In general, a crossover study measures participants under more than one condition. Because the same person contributes measurements in different conditions, the observations are related rather than independent. An analysis that accounts for this relationship can compare within-person changes and may reduce the influence of stable differences between participants. This benefit depends on the design and analysis being implemented appropriately; the registry’s crossover label alone does not establish which statistical method was used.
Condition order can matter in a repeated-condition experiment. Practice, fatigue, or carryover from an earlier condition can affect a later measurement. Random assignment of condition order can help address systematic order effects, but the registry does not report the sequence or the procedure used to randomize it. It also does not describe any washout interval or analysis of period or carryover effects. These details are not reported in the registry record, so their role in the study cannot be assessed.
What would an uncertainty interval convey?
In general, a confidence interval describes the statistical uncertainty around an estimate under the assumptions of the analysis. For a condition contrast, it would help readers assess which values are reasonably compatible with the observed data and model. An interval’s width reflects precision: narrower intervals indicate greater precision than wider intervals. The registry record reports no confidence interval for the primary outcome or any comparison, so the precision of the study’s results cannot be assessed.
A p-value, when reported, addresses how compatible the observed data are with a specified null model under the assumptions used. It does not state the probability that a hypothesis is true, and it does not measure the size or practical importance of an effect. No p-value or tested hypothesis is reported in the registry record. Without estimates and uncertainty measures, a statistical significance interpretation is not possible.
How should the planning illustration be understood?
The record describes a planning illustration based on an observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It says that the effect to detect is a stated fraction of the observed effect. Such illustrations concern hypothetical future planning under their stated assumptions; they are not evidence that the original study had a particular probability of detecting an effect. They are never observed power.
The illustration’s two-arm, equal-allocation framework is distinct from the registered three-condition crossover design. It should not be treated as a reconstruction of the trial’s original design or sample-size justification. The original sample-size justification is not reported in the registry record. The record also contains no numerical planning outputs or observed effect estimates, so the planning assumptions cannot be used to infer a specific required enrollment or the precision achieved in this experiment.
What analysis details are unavailable?
The registry lists zero analyses. It does not report a model, a method for handling repeated measurements, covariates, missing observations, outliers, or the analysis population. It also does not provide the number of observations contributing to each condition or context. These are important because the design includes repeated conditions and the summary describes measurements with and without a distracter. Without such details, readers cannot verify how the primary endpoint was calculated or whether the analysis accounted for the structure of the measurements.
10. Confidence Intervals for Each Arm
No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.
| Arm | Participants | Mean | Standard deviation | 95% CI for the mean |
|---|---|---|---|---|
| Healthy Subjects | 48 | 0.580 | 0.041 | 0.568 to 0.592 |
R code and output
arm <- c("Healthy Subjects")
n <- c(48)
m <- c(0.58)
sp <- c(0.041)
sd <- sp # posted standard deviations
for (i in seq_along(n)) {
se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}
CARM Healthy Subjects 48 0.580 0.041 0.568 0.59211. Multiplicity, Missing Data and Analysis Populations
The study summary describes several performance measurements: maximum force applied to the brake pedal, braking reaction time, and total braking time. It also describes measurements during emergency braking with and without a distracter, and the study includes multiple driving conditions. The registry lists two outcome measures, while the primary endpoint description refers to reaction time and total braking time. It does not explain the relationship among these measures, identify a hierarchy beyond naming a primary endpoint, or report a multiplicity plan.
In general, when several outcomes or comparisons are tested, the chance of at least one apparently notable result can increase if no adjustment or prespecified hierarchy is used. A multiplicity strategy may define which comparison is primary, order tests, or adjust inference. The record does not report whether any such strategy was planned or used. Because no outcome estimates or inferential results are posted, it is not possible to assess how multiplicity affected any reported conclusions.
Missing-data handling is also not reported. The enrollment figure is 48, but enrollment does not show how many participants completed every condition or contributed measurements to each analysis. The record provides no participant flow, completion counts, reasons for missing measurements, or imputation or exclusion method. The primary endpoint population is blank, and the record lists zero analyses. Consequently, the number of participants included in a primary analysis and the treatment of incomplete crossover data cannot be determined.
The record does not specify whether all randomized participants were analyzed as assigned, whether only complete cases were included, or whether any measurements were excluded. It also does not describe whether the analysis population differed by endpoint or simulator context. These omissions limit assessment of potential bias from missing observations and prevent reconstruction of the analysis set. They do not establish that data were missing; they mean the registry record does not report whether or how that issue arose.
12. 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 |
|---|---|---|---|
| Healthy Subjects | 0 | 48 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Healthy Subjects | 0 of 48 |
The registry lists a safety group of 48 healthy subjects. For that group, it records 48 at risk and zero affected for serious adverse events, and 48 at risk and zero affected for other adverse events. In plain terms, the posted safety figures show no affected participants recorded in either of those categories among the listed group.
These entries should be read as registry counts, not as a complete account of how safety was monitored. The record does not report the event-collection procedures, the period over which events were assessed, definitions used for the categories, or whether events were solicited or reported spontaneously. It also does not provide a narrative safety assessment. The death entry is null, so deaths are not reported in the registry record; a null entry should not be interpreted as a confirmed count of zero.
The listed figures do not describe the frequency or severity of particular events, and no serious adverse event terms are listed. They should not be used to infer more than the registry records. In particular, these counts do not establish that no unrecorded events occurred, and they do not provide an assessment outside the study group and safety reporting shown in the record.
13. What the Result Does, and Does Not, Mean
The study’s stated purpose was to evaluate how different lower right limb orthopedic immobilizations relate to braking performance in simulated driving. Its registered conditions were driving with running shoes, a plaster cast, and an Aircast. The study summary says emergency braking was assessed with and without a distracter, and the primary endpoint is named mean breaking time in seconds.
What the registry record does not show is the observed performance under those conditions. It contains no condition-specific means, standard deviations, estimates of contrasts, confidence intervals, or p-values. As a result, the posted record does not establish the direction, size, or statistical precision of any difference. Absence of reported results is not evidence that the conditions produced the same measurements, and it is not evidence that they differed.
The endpoint wording also leaves an interpretive question: its title names mean breaking time, while its description refers to both braking reaction time and total braking time. The record does not define the calculation or identify which of these was the primary measure. Without that definition and the observed estimates, readers cannot tell precisely what numerical performance quantity would be compared.
Even if results were available, the setting would remain important. This was a simulator experiment in healthy volunteers, not a report of real-world driving outcomes in people requiring immobilization. The registry does not report how simulator measurements relate to actual road performance. Nor does it provide enough design and analysis detail to evaluate the handling of repeated conditions, condition order, incomplete observations, or multiple outcomes.
The defensible conclusion from this registry entry is therefore about the study question and its reporting, not about a treatment effect. The record describes a randomized crossover simulator study and its intended braking measures, but does not report the primary outcome results needed to quantify or interpret differences between conditions.
14. Why This Trial Matters Statistically
This trial is statistically notable as a repeated-condition experiment in which the same healthy volunteers were assessed under running-shoe and lower right limb immobilization conditions. That crossover structure makes the dependence among measurements central to analysis. Treating condition measurements as if they came from unrelated groups could fail to use the design information; a suitable analysis would generally account for within-person correlation. The registry record does not say whether or how that was done.
The study also illustrates why endpoint definitions matter. The named primary outcome is mean breaking time, but the description mentions both braking reaction time and total braking time, while the study summary includes maximum brake force. These measures capture distinct aspects of performance. Clear definitions and a reported hierarchy help readers understand which question was primary and how other measures fit into interpretation. The registry does not supply that detail.
Multiple conditions and distracter settings create more than one potential contrast. In general, a prespecified primary comparison and an explicit multiplicity approach help distinguish confirmatory inference from exploratory comparisons. No such plan is reported in the registry record. Because it also provides no estimates or inferential results, statistical significance, effect size, and precision cannot be evaluated.
Finally, the entry shows the difference between study registration and results reporting. The design, enrollment, interventions, and intended outcome provide a useful outline, but a statistical interpretation requires actual outcome data and analysis details. The registry lists zero analyses and does not report condition-specific endpoint values, missing-data handling, or the original sample-size justification. The study therefore raises relevant design and reporting questions without allowing a quantitative conclusion about braking performance.
15. 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 central limitation for interpreting the record is that it contains no numerical primary-outcome results. Means, standard deviations, condition contrasts, confidence intervals, and p-values are not reported. This prevents assessment of direction, magnitude, precision, or statistical evidence for differences in braking performance.
The primary endpoint is not operationally clear from its title and description. The title refers to mean breaking time, while the description mentions braking reaction time and total braking time. The registry does not define how the measure was calculated or specify which time measure was the primary one. Although the summary mentions maximum braking force, the relationship between that measure and the listed outcome measures is not explained.
Important crossover-design details are also absent. The condition order, randomization procedure, washout interval, period effects, and carryover assessment are not reported in the registry record. The record does not specify the statistical model or how repeated observations from the same participants were handled. It does not report the number completing each condition or the analysis population.
The study summary describes measurements with and without a distracter, but the registry does not report whether those contexts were analyzed separately or combined. It also gives no multiplicity plan, missing-data method, or original sample-size justification. The planning assumptions described in the record are not a substitute for that original justification, and they do not provide numerical results for this entry.
Finally, the participants were healthy volunteers and the outcomes were measured in a driving simulator. The record does not report real-world driving outcomes or explain how simulator performance corresponds to driving outside the study setting. These limitations constrain what can be concluded from the registry record even apart from the absence of outcome estimates.
16. Related Tutorials
17. Related Statistical Calculators
18. Sources
- ClinicalTrials.gov: The Effects of Lower Right Limb Orthopedic Immobilization on Driving Performance — NCT00950729.
- Registry record last updated 2015-07-15; status last verified 2015-06.
- Results first posted 2009-08-03.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
19. Record Summary
NCT00950729 is a completed, randomized, unmasked crossover experimental study sponsored by Université de Sherbrooke. The registry records 48 healthy volunteers and compares simulated driving with running shoes, a plaster cast, and an Aircast for lower right limb immobilization. Emergency braking was assessed with and without a distracter.
The primary endpoint is titled mean breaking time measured on a driving car simulator, in seconds, with standard deviation specified as the dispersion measure. The description refers to braking reaction time and total braking time. Recruitment began in 2007-03, primary completion is recorded as 2007-06, and the endpoint timeframe is stated as June 2007 to September 2007.
The registry record does not report numerical primary-outcome results, analysis methods, missing-data handling, or the original sample-size justification. It lists zero analyses. The safety group records zero participants affected for serious and other adverse events among 48 at risk; deaths are not reported in the registry record.