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 Reliability of a Masseter Muscle Prominence Scale and Lower Facial Shape Classification (NCT01821534), a registered phase not stated study. The primary outcome is Inter-rater Reliability Using a Masseter Muscle Prominence Scale (MMPS).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01821534 |
| Phase | Phase not stated |
| Condition | Healthy Volunteers |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 201 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Allergan |
| Results posted | Yes |
2. Clinical Question
Population
Healthy volunteers. The record lists an enrollment of 201. For the primary reliability outcome, the analysis population is described as subjects with at least assessment 1 performed by at least one in-person rater on Day 1.
Intervention
No intervention was administered. This is a measurement-reliability study rather than a trial evaluating a treatment.
Comparator
There is no treatment comparator. The primary outcome examines agreement among raters assessing the same participants, with results assessed separately for the left and right sides of the face.
Primary question
How consistently do raters assess masseter muscle prominence using the Masseter Muscle Prominence Scale on Day 1? The registry record identifies Kendall’s W and a 95% confidence interval as the statistic and uncertainty measure, but does not report their values.
The study’s stated purpose also includes evaluating intra-rater reliability and the Lower Shape Classification for lower facial shape. The registry summary does not give further detail about how those evaluations were conducted. In particular, the primary outcome information concerns inter-rater reliability for the Masseter Muscle Prominence Scale, not a comparison of treatments or a test of whether a particular facial appearance is preferable.
Reliability concerns the consistency of measurements under the stated assessment conditions. For this study, the primary question is whether physicians’ ratings of masseter prominence tend to agree. The record states that eight physicians rated each subject. It defines ratings for each side of the face on an ordinal scale running from 1=minimal to 5=very marked. The outcome information says that the left and right sides were evaluated separately.
The record does not report a numerical estimate of agreement, so it cannot establish from the posted results how much agreement was observed. Nor does the primary outcome alone answer whether the scale measures the intended clinical construct accurately, whether ratings would remain consistent in other settings, or whether the separate lower facial shape classification is reliable. Those questions require evidence beyond the primary endpoint description.
3. Trial Design
The registry describes a completed study with an enrollment of 201 and healthy volunteers as the condition. The listed study start is 2013-03, and primary completion is recorded as 2013-05. The intervention is listed as No Intervention, and the arm description states that no treatment was administered. The design is therefore about assessment consistency, not a treatment contrast.
The primary outcome is inter-rater reliability for the Masseter Muscle Prominence Scale (MMPS), measured on Day 1. According to the outcome description, eight physicians rated each subject. Ratings were considered separately for the left and right sides of the face. Kendall’s coefficient of concordance, Kendall’s W, was used to assess agreement among raters.
The outcome description further states that the overall left- and right-side Kendall W statistics were derived using the average of assessment 1 and assessment 2, rounded to the nearest whole integer for each subject and each clinician. The reliability population is described as all subjects with at least assessment 1 performed by at least one in-person rater on Day 1. The record does not explain whether every enrolled volunteer met that criterion or how many observations were included in the primary analysis.
The brief summary says the study will evaluate both inter-rater and intra-rater reliability for the MMPS and a Lower Shape Classification for lower facial shape. However, the primary outcome details focus on inter-rater reliability for the MMPS. The registry record does not report the detailed assessment schedule or analysis procedures for the other stated reliability questions.
Allocation is not stated, and the registry identifies the study as not being a randomized comparison. There are no like-for-like treatment arms to compare. The record lists 4 outcome measures and 0 analyses. A trial-specific sample-size justification, protocol, and fuller statistical plan are not reported in the registry record. The listed study status is COMPLETED.
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
| Stage | All Participants |
|---|---|
| STARTED | 201 |
| COMPLETED | 201 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: Reliability population: all subjects with at least assessment 1 performed by at least 1 in-person rater on day 1
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 | All Participants |
|---|---|---|
| Participants analysed | 201 | |
| Age, Continuous | Years | 35.5 (SD 11.43) |
| Sex: Female, Male: Female | Participants | 128 |
| Sex: Female, Male: Male | Participants | 73 |
6. Primary Endpoint
The registry lists the primary outcome as Inter-rater Reliability Using a Masseter Muscle Prominence Scale (MMPS), measured over Day 1.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | 95% Confidence Interval |
| Unit | Kendall's W |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is inter-rater reliability using the Masseter Muscle Prominence Scale, reported as Kendall’s W with a 95% confidence interval. The scale is described as an ordinal rating of masseter muscle prominence on each side of the face, ranging from 1=minimal to 5=very marked. The endpoint concerns how concordant the physicians’ ratings are, rather than a change in a participant or a difference between treatments.
The registry says that eight physicians rated each subject and that left and right sides were assessed separately. It also says the overall Kendall W statistics were derived from the average of assessment 1 and assessment 2, rounded to the nearest whole integer for each subject and each clinician. The stated timeframe is Day 1. The reliability population includes subjects with at least assessment 1 performed by at least one in-person rater on that day.
Reliability is useful because a scale intended for assessment depends on measurements being sufficiently consistent across the people applying it. General statistical interpretation: a concordance statistic summarizes how closely ratings follow a common ordering or pattern, while its confidence interval conveys uncertainty around the estimate. Neither measure alone establishes that a scale captures the intended construct accurately; consistency and validity are different properties.
The registry record does not report the observed Kendall W estimates or confidence intervals. Consequently, the endpoint definition explains what was intended to be measured, but the posted record does not show the numerical degree or precision of inter-rater agreement.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a reliability study, not a randomized treatment comparison. Its primary outcome is Kendall’s W for inter-rater agreement on the MMPS, calculated separately for the left and right sides of the face. The outcome description states that eight physicians rated each subject and that the ratings were handled using the stated averaging and rounding procedure. These details define the intended analysis, but the record does not include the resulting Kendall W estimates.
Without the point estimates and 95% confidence intervals, the observed agreement and its precision cannot be characterized. The record supplies an interpretation scale for Kendall’s W: values at or below 0 are classified as poor; values above 0 through 0.2 as slight; above 0.2 through 0.4 as fair; above 0.4 through 0.6 as moderate; above 0.6 through 0.8 as substantial; and above 0.8 through 1.0 as almost perfect. These are the prespecified interpretive categories stated in the outcome description. They cannot be applied to the study’s results without the actual estimates.
A confidence interval is useful because a point estimate alone does not convey how uncertain the estimate may be. General statistical interpretation: a narrower interval indicates greater precision under the model and method used; a wider interval indicates less precision. An interval can also show whether plausible values span more than one interpretive category. The registry record gives the confidence-interval level but not the interval limits, so no such assessment is possible from the posted results.
The listed analysis population is subjects with at least assessment 1 performed by at least one in-person rater on Day 1. This eligibility description does not give the number included in the analysis, the amount of incomplete rating information, or whether the analysis used all eligible observations. Enrollment is reported as 201, but enrollment alone does not establish how many observations contributed to each side-specific estimate.
The study summary also describes an aim to evaluate intra-rater reliability and a lower facial shape classification. The primary endpoint information does not report those results. It would therefore be inappropriate to infer that the primary outcome represents the performance of every assessment tool or every type of reliability examined in the study.
The adverse-event record lists 0 serious adverse events and 0 other adverse events among 201 participants at risk in the All Participants group. These are registry counts, not reliability findings. The record does not report deaths as a numerical count. Overall, the posted information describes the planned measurement question and some analysis details, but does not include outcome estimates needed to judge the observed reliability.
9. Statistical Methods Explained
What does inter-rater reliability mean?
Inter-rater reliability concerns the consistency of ratings made by different raters assessing the same subjects. In this study, the stated primary question is agreement among physicians rating masseter muscle prominence with the MMPS. The record says eight physicians rated each subject. Because the measure is ordinal, the ratings represent ordered categories rather than a continuous measurement scale with equal distances necessarily established between categories.
General statistical explanation: reliability statistics condense patterns of agreement into a summary measure. A reliability estimate should be interpreted in light of the actual rating procedure, the people being rated, the raters, and the range of ratings represented in the data. An estimate does not automatically generalize to different raters, settings, or populations. The registry record does not report evidence about such generalizability beyond the described assessment.
What does Kendall’s W describe?
Kendall’s coefficient of concordance, written as Kendall’s W, is an agreement statistic suited to assessing concordance among rankings or ordered ratings. In general, it summarizes how consistently multiple raters order the subjects. Its possible range in the registry’s stated interpretation runs from 0 to 1, with larger values corresponding to stronger concordance under that interpretation. The record defines categories from poor through almost perfect, but gives no observed value to place in those categories.
Kendall’s W is not a treatment effect. It does not estimate a difference between intervention and control groups, and it does not by itself establish the accuracy or clinical usefulness of a rating scale. It addresses a form of consistency in the assessments analyzed. A high level of concordance would not by itself prove that the ratings are correct; conversely, an estimate of concordance says nothing on its own about the consequences of using the scale.
Why are the sides analyzed separately?
The primary outcome description states that reliability was calculated separately for the left and right sides of the face. Separate results can preserve the side-specific nature of the ratings rather than combining them into a single endpoint. The record does not report the resulting estimates, so it is not possible to compare the agreement for the two sides or determine whether either estimate differed in precision.
The description says the overall side-specific Kendall W statistics were derived using the average of assessment 1 and assessment 2, rounded to the nearest whole integer for each subject and each clinician. This is part of the stated processing of ratings. The registry record does not explain the rationale for this procedure, report alternative analyses, or describe how disagreements between assessments were otherwise handled. No additional procedure should be inferred from the endpoint description.
How should the confidence interval be read?
The 95% confidence interval is an uncertainty interval associated with the Kendall W estimate. General statistical explanation: under the assumptions of the analysis, a confidence interval describes the range of values compatible with the observed data and method at the stated confidence level. It is not a guarantee that the true value lies within the particular interval, and it does not repair limitations in sampling or measurement.
For this endpoint, the interval would help readers assess the precision of the agreement estimate and whether its plausible values fall within one or more of the registry’s interpretation categories. The interval limits are not reported in the registry record. Therefore, the precision of the estimate and the stability of its categorical interpretation cannot be assessed.
What can be said about planning and power?
The record’s sample-size assumptions describe 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; the effect to detect is described as a stated fraction of the observed effect. Such illustrations are planning calculations, not observed power and not necessarily the design used to conduct a study. The record states that sample sizes for non-time-to-event outcomes are expressed as participants per arm. It does not report a trial-specific sample-size justification or establish a randomized two-arm design. This trial is not a randomized comparison, and its listed intervention is No Intervention.
For a reliability study, planning and analysis need to reflect the rating structure and intended reliability estimand. General statistical explanation: the number of subjects, number of raters, missing ratings, and expected distribution of rating categories can affect precision. The registry record states the number of physicians who rated each subject but does not report the analysis sample size, the distribution of scores, or a reliability-based precision target.
Why can variation affect agreement estimates?
General statistical explanation: reliability estimates depend not only on whether raters disagree, but also on how much the subjects differ from one another on the measured attribute. If most subjects receive similar ratings, the data may contain less variation for distinguishing subjects, which can affect a reliability summary. When observations are clustered by subject or rater, the dependence structure also matters; treating related observations as independent can misrepresent uncertainty. The registry record does not describe a model for such dependence or report the data needed to evaluate these issues.
The outcome description provides the chosen statistic and the derivation of the ratings used for it, but the numerical results are absent. Thus, the methods can be described at the level recorded, while the size, uncertainty, and practical interpretation of the observed agreement remain unknown.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 4 outcome measures and 0 analyses. It identifies inter-rater reliability for the MMPS as the primary outcome, but the brief summary also names intra-rater reliability and the Lower Shape Classification as study objectives. The detailed information available for the primary endpoint does not establish how all outcomes were prioritized or analyzed. A multiplicity adjustment or a plan for interpreting several outcomes is not reported in the registry record.
Multiplicity matters when several hypotheses or outcomes are examined, because the chance of at least one apparently notable result can increase as the number of analyses grows. General statistical explanation: an analysis plan can address this by identifying primary outcomes in advance and specifying how other outcomes will be interpreted or adjusted. Without a reported plan and numerical analyses, it is not possible to determine how multiplicity was handled or whether it affected interpretation.
The stated reliability population comprises subjects with at least assessment 1 performed by at least one in-person rater on Day 1. This defines an eligibility condition for the primary analysis population, but the record does not report the number meeting it or the number with complete ratings. The handling of missing assessments, partial rater data, and any exclusions is not reported in the registry record.
The record says that the average of assessment 1 and assessment 2 was rounded to the nearest whole integer for each subject and clinician when deriving the overall Kendall W statistics. It does not state what happened when one assessment was absent, whether that situation occurred, or whether other missing-data procedures were used. No assumptions about missingness or imputation should be inferred.
A fuller protocol, statistical analysis plan, interim-analysis plan, and sample-size justification are not reported in the registry record. The listed planning assumptions do not establish the study’s actual analysis plan or a trial-specific design calculation.
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 |
|---|---|---|---|
| All Participants | 0 | 201 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| All Participants | 0 of 201 |
The registry lists 201 participants at risk in the All Participants group. It records 0 serious adverse events and 0 other adverse events for that group. These are the posted event counts and at-risk count; the record does not provide additional detail about event definitions, observation time, or how events were collected.
The deaths entry is null, so a death count is not reported in the registry record. A null entry should not be read as a numerical count of zero. The zero counts for serious and other adverse events are separate entries and should not be extended to outcomes that are not reported.
These figures are descriptive safety reporting, not a comparison between treatment groups. The study lists No Intervention and has no like-for-like treatment comparator. The figures therefore cannot estimate a difference in risk between treatments. They also do not establish the absence of events beyond what is recorded in this registry entry. No percentages or rates are reported because the registry record gives counts and an at-risk group, not a reported rate analysis.
12. What the Result Does, and Does Not, Mean
The registry record establishes that the study’s primary measurement question concerned inter-rater reliability of the MMPS among healthy volunteers on Day 1. It specifies Kendall’s W, separate assessment of the left and right sides, a 95% confidence interval, and an interpretation scale. It also records that eight physicians rated each subject and describes how assessment 1 and assessment 2 were averaged and rounded for the overall side-specific statistics.
Those details clarify the target of the primary endpoint, but they do not reveal the observed level of agreement. The registry record does not report the Kendall W values or confidence-interval limits. It is therefore not possible to say whether agreement was poor, slight, fair, moderate, substantial, or almost perfect under the stated categories, nor how precise any estimate was.
The study summary names intra-rater reliability and a Lower Shape Classification as additional aims. Their numerical results and detailed methods are not reported in the registry record. The primary endpoint description cannot be taken as evidence for the reliability of those other assessments.
General statistical interpretation: reliability is one property of a measurement procedure. It is not interchangeable with validity, which concerns whether a measure captures the intended construct. Nor does reliability alone show that using a rating scale changes decisions or improves outcomes. The record does not address those questions, and no treatment was administered.
The enrollment and safety counts describe the registry entry but do not fill the gap in the primary reliability results. The study is listed as completed, yet the posted record does not report the numerical endpoint findings needed to judge its observed measurement agreement. The appropriate conclusion is limited: the record describes the reliability analysis that was intended, while the magnitude and precision of the resulting agreement remain unreported.
13. Why This Trial Matters Statistically
Reliability is central to interpreting any rating-based assessment: if different raters produce inconsistent assessments, comparisons across subjects or settings may be difficult to interpret. This study is statistically relevant because it identifies an explicit inter-rater reliability question for an ordinal scale, names Kendall’s W as the agreement statistic, and describes separate results for each side of the face.
The record also documents elements that help define the estimand: the assessment timeframe is Day 1, eight physicians rated each subject, and the primary reliability population is based on having at least assessment 1 from at least one in-person rater. It describes a particular averaging and rounding procedure before the overall side-specific statistics were derived. These choices matter because reliability estimates depend on which ratings and subjects contribute to an analysis.
At the same time, the record illustrates why a methods description is not a substitute for results. Without the Kendall W estimates and their confidence intervals, readers cannot judge the degree of agreement or its precision. A completed status and a defined analysis do not communicate the observed performance of the scale when the numerical findings are absent.
The study also distinguishes, at least in its stated aims, inter-rater reliability, intra-rater reliability, and classification of lower facial shape. These are related measurement questions but are not identical. Evidence about one cannot automatically be generalized to the others. The registry’s primary outcome details apply specifically to inter-rater reliability for the MMPS.
Statistically, the record is useful for identifying what was intended to be measured and for making clear which interpretive framework was specified. Its importance is also a reminder that transparent reporting should include estimates, uncertainty, analysis populations, and missing-data handling. Those results and procedures are not fully reported in this registry record.
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 the primary Kendall W estimates or their 95% confidence intervals. As a result, neither the magnitude nor the precision of inter-rater agreement can be evaluated from the posted information. The stated categories for interpreting W do not resolve this gap without the numerical results.
The record describes an analysis population of subjects with at least assessment 1 performed by at least one in-person rater on Day 1, but does not report how many subjects met this definition or contributed to each side-specific estimate. Enrollment is recorded as 201, but the analysis denominator and completeness of ratings are not reported. The extent and handling of missing assessments are also not reported in the registry record.
The outcome description gives a rating-processing procedure involving the average of assessment 1 and assessment 2, rounded to the nearest whole integer. The record does not explain how incomplete pairs were handled, whether the procedure was prespecified in a protocol, or whether sensitivity analyses were conducted. A protocol and statistical analysis plan are not reported in the registry record.
The brief summary includes intra-rater reliability and a Lower Shape Classification, but the primary outcome details concern inter-rater reliability of the MMPS. Numerical findings and analysis details for the other stated objectives are not reported in the registry record. Findings for the primary endpoint, even if available, would not automatically resolve those separate questions.
The registry identifies healthy volunteers and a no-intervention design. The record does not establish how well the findings would generalize to other populations or assessment settings. It also does not report evidence about validity. These limitations should be considered separately from the absence of numerical reliability results.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Reliability of a Masseter Muscle Prominence Scale and Lower Facial Shape Classification — NCT01821534.
- Registry record last updated 2014-04-30; status last verified 2014-03.
- Results first posted 2014-04-30.
- 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 a completed, no-intervention study of reliability assessments in healthy volunteers, with enrollment of 201. The primary outcome is inter-rater reliability for the Masseter Muscle Prominence Scale on Day 1, using Kendall’s W and a 95% confidence interval, separately for the left and right sides of the face. Eight physicians rated each subject, and the endpoint description specifies how assessment 1 and assessment 2 were averaged and rounded for the overall statistics.
The record’s interpretation categories range from poor to almost perfect. However, the numerical Kendall W estimates and confidence intervals are not reported in the registry record. The summary also names intra-rater reliability and the Lower Shape Classification as study aims, without giving their results in the primary endpoint details.
The record lists 4 outcome measures and 0 analyses. Safety entries list 0 serious adverse events and 0 other adverse events among 201 participants at risk; deaths are not reported as a numerical count. The study’s listed status is COMPLETED, but the posted information is insufficient to determine the observed magnitude or precision of its primary reliability findings.