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 MightySat - Clinical Performance Comparison Study (NCT03239574), a na phase not stated study. The primary outcome is Accuracy of RRp Determination.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03239574 |
| Phase | Phase not stated |
| Condition | Healthy |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 34 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Masimo Corporation |
| Results posted | Yes |
2. Clinical Question
Population
Healthy subjects enrolled in a device-performance study. The registry record reports an enrollment of 34.
Intervention
Participants received the MightySat investigational pulse oximeter, with respiratory rate from pleth (RRp) measured by the device.
Comparator
The reference was respiratory rate (RR). The stated accuracy calculation compares MightySat RRp measurements with the reference; the study is not described as having a separate control group.
Primary question
How closely does MightySat RRp agree with the RR reference under the study conditions, as assessed by arithmetic root mean square error (Arms)?
The study description says participants would be asked to breathe at specified rates ranging from 5 to 30 breaths per minute. This creates a measurement-performance question: the focus is the difference between a device reading and its reference, rather than a comparison of health outcomes between treatment groups.
The registry identifies the condition as Healthy and the device as MightySat. It does not report the exact reference method, how measurements were scheduled, or whether all specified breathing rates were completed by every participant. Those details are not reported in the registry record.
The primary question is therefore narrowly about measurement accuracy in the study setting. The registry record does not report the resulting Arms value or other analysis results, so the magnitude and precision of agreement cannot be assessed from the record.
3. Trial Design
This completed study is titled MightySat - Clinical Performance Comparison Study and is sponsored by Masimo Corporation. The registry lists a single-group model, with participants enrolled in the MightySat test group and receiving the investigational pulse oximeter. Enrollment was 34. The study dates are 2017-07-10 for start and 2017-07-20 for primary completion.
Allocation is recorded as NA and masking as NONE. The registry also notes that this is not a randomized comparison and that the arms are not a like-for-like control comparison. The comparison described for the primary outcome is between the device’s RRp measurement and a respiratory-rate reference, not between randomized groups.
Participants were to breathe at specified rates ranging from 5 to 30 breaths per minute. The primary outcome timeframe is approximately 30-40 minutes. The record does not report the exact sequence of breathing instructions, the number of measurements taken at each rate, or how the reference measurement was obtained.
The design is suited to describing device-reference measurement differences under the conditions recorded, but the registry entry does not supply an endpoint estimate or analysis results. It also does not report a protocol rationale for the enrollment target, a sample-size justification, or details about recruitment and eligibility beyond the condition being Healthy. Those details are not reported in the registry record.
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 | MightySat Test Group |
|---|---|
| STARTED | 34 |
| COMPLETED | 34 |
| 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 | MightySat Test Group |
|---|---|---|
| Participants analysed | 34 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 34 |
| Age, Categorical: >=65 years | Participants | 0 |
| Sex: Female, Male: Female | Participants | 10 |
| Sex: Female, Male: Male | Participants | 24 |
| Race/Ethnicity, Customized: African American | Participants | 10 |
| Race/Ethnicity, Customized: Asian or Pacific Islander | Participants | 3 |
| Race/Ethnicity, Customized: Caucasian | Participants | 15 |
| Race/Ethnicity, Customized: Hispanic | Participants | 5 |
| Race/Ethnicity, Customized: Middle Eastern | Participants | 1 |
| Region of Enrollment: United States | participants | 34 |
6. Primary Endpoint
The registry lists the primary outcome as Accuracy of RRp Determination, measured over approximately 30-40 minutes.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | breaths per minute |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is Accuracy of RRp Determination, measured in breaths per minute. Its stated purpose is to quantify how closely the MightySat respiratory rate from pleth measurement matches the respiratory-rate reference during the study timeframe of approximately 30-40 minutes.
The registry defines accuracy using arithmetic root mean square error, or Arms. For each sample, the reference RR is subtracted from the MightySat RRp measurement. The average of these differences is the bias, and the standard deviation of the differences is the precision. Arms is calculated as the square root of the sum of the squared bias and squared precision.
This measure is useful because it combines systematic offset and variability in one summary: a device can have a small average difference but still show substantial scatter across samples. Conversely, the bias alone describes only the average direction and size of the difference. Arms does not, by itself, explain the distribution of individual differences or establish whether a particular error is acceptable for a specific use.
The registry record defines the endpoint but does not report its observed value, uncertainty interval, or analysis results. A performance conclusion cannot be drawn from the endpoint definition alone.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record establishes what the study intended to measure: the accuracy of MightySat RRp against a respiratory-rate reference in healthy subjects. It also gives the calculation used for the primary endpoint. It does not report the observed Arms value or any other endpoint result. Consequently, there is no posted estimate from which to describe the size of measurement error, its direction, or its precision.
Arms is a combined measure. Bias represents the average difference between the device and reference using the stated subtraction order; precision represents the spread of those differences. The combined statistic can capture both systematic offset and random variation, but it does not replace examination of the two components. The registry record does not report either component separately, so their relative contribution cannot be assessed.
The comparison is a measurement comparison, not an intervention-effect comparison. Participants received MightySat, and the reference measurement serves as the basis for evaluating device readings. Since the registry records a single group and no randomized control comparison, the design does not estimate a treatment effect between groups. The record itself cautions that the arms are not a like-for-like control comparison.
The study population is described as healthy. Any interpretation therefore concerns the study setting and population described in the registry; the entry does not establish how measurements would perform in other populations or settings. Details such as the reference method, handling of repeated samples, and criteria for acceptable performance are not reported in the registry record.
The status is COMPLETED, but completion does not supply an outcome result. The registry lists one outcome measure and zero analyses. The endpoint estimate, its uncertainty, and the analysis details are not reported in the registry record. Without those results, neither the direction nor magnitude of observed agreement can be evaluated. The endpoint definition should be read as a plan for quantifying accuracy, not as evidence about the observed performance.
9. Statistical Methods Explained
The statistical method specified for the primary endpoint is arithmetic root mean square error (Arms), based on differences between MightySat RRp and reference RR measurements. The registry describes a sequence of calculations: form the sample differences, summarize their average as bias, summarize their standard deviation as precision, and combine bias and precision into Arms.
What does bias represent?
Bias is the average of the differences, with each difference defined as MightySat RRp minus reference RR. A positive average would mean the device readings are higher than the reference on average; a negative average would mean they are lower on average. These are interpretations of the stated subtraction order, not reported findings. The record does not report an observed bias value.
An average difference is informative about systematic offset, but it can conceal variation among measurements. Differences that fall on both sides of the reference can average to a small value even when individual observations vary considerably. Thus, bias alone is not a complete account of agreement. In this study’s description, the standard deviation of the differences adds information about their spread.
What does precision represent?
Here, precision is defined as the standard deviation of the sample differences. In general statistical terms, a standard deviation describes how dispersed observations are around their average. A relatively small spread would mean differences tend to cluster more tightly around the average difference; a larger spread would indicate more variability. The registry does not report the precision estimate, so that pattern cannot be characterized for this study.
Precision in this endpoint is a statistical description of measurement differences. It should not be confused with the number of decimal places in a displayed measurement, nor does it alone establish that a measurement is accurate. Accuracy can be affected by both average offset and variation.
Why combine bias and precision?
Arms combines the squared bias and squared precision, then takes the square root of their sum. Squaring makes the contribution of each component nonnegative, so positive and negative bias do not cancel out the variability term. The combined statistic expresses the overall size of error in the units of the respiratory-rate measurement, breaths per minute. If average bias is small but spread is large, the combined error can still reflect that spread; if spread is limited but bias is substantial, the combined statistic reflects the offset.
Arms is a concise summary, not a complete description of the error distribution. It does not show whether errors are concentrated at particular instructed breathing rates, whether outliers occurred, or whether there are patterns across participants. The registry record does not report such breakdowns or plots of individual differences. Nor does the endpoint definition specify an acceptance threshold. Without a threshold and an observed estimate, the term accuracy cannot be translated into a judgment about whether performance met a prespecified criterion.
What can confidence intervals add?
In general, a confidence interval describes uncertainty around an estimated quantity under the statistical procedure used. It helps distinguish a point estimate from the range of values compatible with the data and method. No confidence interval for Arms, bias, or precision is reported in the registry record. The number of observations contributing to the endpoint and the method for estimating uncertainty are also not reported in the registry record.
Measurements collected from the same participant may be related rather than statistically independent. In general, analysis methods need to account for clustering or repeated observations when that dependence is present. The endpoint description refers to a number of samples, but does not report the analysis unit, any adjustment for within-participant dependence, or the structure of the data. Those analysis details are not reported in the registry record.
How should planning illustrations be read?
Any sample-size planning illustration uses assumptions rather than documenting achieved power. The listed assumptions are a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a stated fraction of the observed effect. These are planning conventions, not evidence that the study had a particular probability of detecting an effect. The registry record does not report an endpoint estimate, so the observed effect underlying such an illustration cannot be assessed from the outcome information in the record. For non-time-to-event outcomes, planning quantities are expressed as participants per arm; time-to-event illustrations refer to total events. These planning conventions do not alter the single-group design recorded for this study.
10. Multiplicity, Missing Data and Analysis Populations
The registry identifies one primary outcome measure, Accuracy of RRp Determination, and lists zero analyses. It does not report a results analysis for that outcome. The presence of a defined primary measure does not establish that a complete statistical analysis plan was registered or followed.
Multiplicity concerns arise when several outcomes, comparisons, subgroups, or repeated analyses are examined, because the chance of a chance-positive finding can increase across analyses. The record does not report a multiplicity adjustment, a hierarchy among outcomes, or a plan for subgroup or interim analyses. Whether any such procedures were planned or conducted is not reported in the registry record.
The registry record does not describe missing-data handling, exclusions from the endpoint analysis, or the analysis population used. It does not report how incomplete measurements, unusable readings, or deviations from the instructed breathing rates were handled. It also does not state whether all enrolled participants contributed data to the primary endpoint. These details are not reported in the registry record.
For a measurement study, it is also important to know how many paired device-reference observations contributed to the estimate and whether repeated observations within a participant were accounted for. Neither the number of analyzed samples nor the analysis method for possible within-participant dependence is reported in the registry record. These omissions limit assessment of the precision and reproducibility of the intended analysis.
Accordingly, the available information defines the primary metric and gives a design description, but does not allow evaluation of multiplicity control, missingness, or the analysis set. The estimate and its uncertainty are not reported in the registry record.
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 |
|---|---|---|---|
| MightySat Test Group | 0 | 34 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| MightySat Test Group | 0 of 34 |
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 |
|---|---|
| MightySat Test Group | 0 of 34 |
The registry lists the MightySat Test Group with 34 participants at risk for serious adverse events and 0 serious adverse events. It also lists 34 at risk for other adverse events and 0 other adverse events, with 0 deaths. No serious adverse-event terms are listed.
These are the safety counts recorded for this study group. They are not evidence about the device’s respiratory-rate accuracy, which is the primary endpoint, and they do not substitute for an accuracy estimate. The registry does not report the method or duration of adverse-event surveillance, event definitions, or details about how safety information was collected. Those details are not reported in the registry record.
A zero count in a completed registry entry means that no events are listed in that category for the recorded group; it should not be interpreted as proof that an event is impossible or that risk is absent. The record’s safety figures also do not describe performance outside the study conditions or population.
12. What the Result Does, and Does Not, Mean
The record describes a device-performance study in healthy subjects, with MightySat RRp measurements compared against a respiratory-rate reference. It specifies a transparent accuracy calculation based on average difference and variation in differences. These details clarify the question the study was designed to address.
The record does not report the primary endpoint estimate, its bias and precision components, an uncertainty interval, or analysis results. As a result, it is not possible to characterize how close the device readings were to the reference, how much individual measurements varied, or how certain any estimate would be. The study status of COMPLETED does not fill this gap.
The design also sets limits on what the record can address. This is a single-group device study, not a randomized comparison of two treatments. Its comparator is the reference measurement used for evaluating RRp, rather than a separate control group. The described population is healthy, and the specified breathing rates range from 5 to 30 breaths per minute. The entry does not report performance in other populations or conditions.
Arms is a summary of error, not a complete account of every measurement or a standalone judgment of clinical acceptability. The registry does not state a threshold for acceptable accuracy, report the reference method, or provide details about the number and distribution of observations. Those matters are not reported in the registry record.
Thus, the record supports a description of the intended measurement comparison and its statistical definition, but not a conclusion about the observed accuracy or its practical significance. No medical conclusion follows from the endpoint definition or the absence of posted endpoint results.
13. Why This Trial Matters Statistically
This study illustrates why device accuracy should be defined in terms that separate systematic offset from variability. The registry’s Arms definition combines the average difference between device and reference with the spread of those differences. Considering both components is important: an average near the reference does not necessarily mean individual readings are consistently close, and a narrow spread does not rule out a systematic offset.
It also highlights the importance of distinguishing a measurement reference from a randomized control group. MightySat readings are compared with RR reference measurements, but the registry describes a single group and explicitly notes that this is not a like-for-like control comparison. The study therefore addresses agreement between measurements, not comparative effects of assigned treatments.
The study conditions matter to interpretation. Participants are described as healthy and asked to breathe at specified rates from 5 to 30 breaths per minute. Results, if reported, would need to be understood in relation to those conditions. The registry does not report a reference method, an acceptable-error threshold, or detailed analysis procedures, all of which can help readers judge the meaning and limits of a performance estimate.
Finally, a clearly defined endpoint is not the same as a reported result. The registry gives the calculation but no observed estimate or analysis results. This distinction is central to evidence appraisal: a protocol-level description explains what was meant to be measured, while results are needed to assess what the study observed. Here, the statistical framework is described more fully than the outcome evidence.
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 statistical interpretation is that the registry defines the primary endpoint but does not report its result. There is no Arms estimate, bias estimate, precision estimate, or uncertainty interval in the record. Therefore, the size and variability of measurement error cannot be evaluated.
The record describes a single-group design with no masking and no randomized control comparison. The reference measurement provides a basis for evaluating the device reading, but the registry does not report how the reference was generated or whether its own measurement error was considered. The exact protocol for taking measurements and managing repeated samples is also not reported in the registry record.
The listed population is healthy, and the study description concerns instructed breathing rates ranging from 5 to 30 breaths per minute. The record does not report how the findings might apply beyond those conditions. It also does not report an acceptable-performance threshold, making it impossible to determine from the endpoint definition alone what level of error would meet a prespecified criterion.
Further details important for reproducibility are absent: the number of paired observations analyzed, missing-data procedures, exclusions, analysis-population definition, and any adjustment for possible dependence among repeated measurements. The statistical analysis plan and sample-size justification are not reported in the registry record. These gaps limit assessment of both the intended inferential method and the precision of any result.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: MightySat - Clinical Performance Comparison Study — NCT03239574.
- Registry record last updated 2020-12-31; status last verified 2020-12.
- Results first posted 2020-12-31.
- 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
NCT03239574 is a completed, single-group device-performance study sponsored by Masimo Corporation. It enrolled 34 healthy subjects and evaluated respiratory rate from pleth (RRp) measured with the MightySat investigational pulse oximeter against a respiratory-rate reference. The recorded study dates are 2017-07-10 to 2017-07-20.
The primary endpoint, Accuracy of RRp Determination, is defined in breaths per minute using arithmetic root mean square error. The registry describes bias as the average device-reference difference and precision as the standard deviation of those differences, with Arms combining the two components.
The registry record does not report an endpoint estimate, analysis results, uncertainty interval, or detailed statistical analysis plan. It lists 0 serious adverse events, 0 other adverse events, and 0 deaths in the MightySat Test Group.