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 PortionSize Smartphone App Pilot (PS Pilot) (NCT04494971), a registered phase not stated study. The primary outcome is Validity of Portion Size at Estimating Energy Intake in Laboratory Conditions.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04494971 |
| Phase | Phase not stated |
| Condition | Dietary Habits |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 15 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Pennington Biomedical Research Center |
| Results posted | Yes |
2. Clinical Question
Population
The registry record lists 15 enrolled participants and identifies dietary habits as the condition. It does not further describe participant characteristics or eligibility criteria.
Intervention
Participants used the PortionSize smartphone app to estimate energy intake from a simulated meal. The stated primary measurement concerns one simulated meal collected on one day.
Comparator
App measurements were compared with weighed values collected in the laboratory. The registry describes weighed values as the criterion measure; it does not describe a separate randomized control group.
Primary question
How closely does PortionSize estimate energy intake, in kcal, compared with weighed values under laboratory conditions? The registry lists this as a validity question but reports no numerical answer.
The study objective also mentions preliminary reliability and perceived participant satisfaction. Those broader aims matter when considering what an app pilot could investigate: validity concerns agreement with a reference measurement, reliability concerns consistency, and satisfaction concerns participants’ perceptions. These are distinct questions and require distinct measures. The registry’s named primary measure is specifically about validity against weighed values, not a general assessment of every app function.
The record does not give further details about the participants, the meal, or the app’s estimation procedure. It therefore does not establish how representative the laboratory task is of other eating situations, nor does it support conclusions about use outside the study conditions. The clinical question is narrow: the accuracy of the app’s estimate relative to a laboratory criterion for a single simulated meal. No numerical outcome results are reported in the registry record, so the degree of agreement cannot be described.
3. Trial Design
The PortionSize Smartphone App Pilot is listed as a completed study sponsored by Pennington Biomedical Research Center. The registry gives a total enrollment of 15. The study start date is 2020-08-31, and the primary completion date is 2020-11-20. These dates describe the registered study timeline; they do not supply information about when each participant was assessed or how long any individual took part.
The primary measure compares PortionSize measurements with weighed values in laboratory conditions. The record calls the weighed values the criterion measure and specifies a simulated meal collected on one day. The design is therefore presented as an assessment of app estimates against a reference measurement, rather than as a treatment comparison intended to estimate a difference between randomized groups. The registry does not state an allocation method, and it does not report a randomized comparison. It identifies a Study Cohort for the safety figures.
The brief objective names preliminary validity, reliability, and perceived participant satisfaction. However, the primary outcome description is limited to validity of portion size at estimating energy intake. The registry lists two outcome measures but no analyses. It does not report how reliability or satisfaction were measured, or provide numerical findings for those outcomes.
The registry record does not report the protocol details needed to characterize recruitment, eligibility, blinding, app-use instructions, meal composition, or the handling of repeated measurements. Nor does it report a statistical analysis plan or a sample-size justification for the study itself. A planning framework based on a two-arm comparison is not a description of this cohort-based validation setup. Consequently, the enrollment and dates describe the registered pilot, but do not establish the precision or representativeness of its findings.
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 | Study Cohort |
|---|---|
| STARTED | 15 |
| COMPLETED | 15 |
| 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 | Study Cohort |
|---|---|---|
| Participants analysed | 15 | |
| Age, Categorical: <=18 years | Participants | NA |
| Age, Categorical: Between 18 and 65 years | Participants | 15 |
| Age, Categorical: >=65 years | Participants | NA |
| Age, Continuous | years | 28 (SD 12.2) |
| Sex: Female, Male: Female | Participants | 11 |
| Sex: Female, Male: Male | Participants | 4 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 0 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 15 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 1 |
| Race (NIH/OMB): White | Participants | 14 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Region of Enrollment: United States | participants | 15 |
6. Primary Endpoint
The registry lists the primary outcome as Validity of Portion Size at Estimating Energy Intake in Laboratory Conditions, measured over 1 simulated meal collected on one day.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | kcal |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is titled “Validity of Portion Size at Estimating Energy Intake in Laboratory Conditions.” It is a continuous measure expressed in kcal, with a mean and standard deviation specified as the summary form. The timeframe is one simulated meal collected on one day. The endpoint compares measurements from PortionSize with weighed values, which the registry identifies as the criterion measure.
This kind of endpoint is used to assess whether an app’s estimate corresponds to a reference measurement under the conditions studied. The mean describes the average value within the measurement group being summarized, while the standard deviation describes the spread of individual values around that mean. Neither statistic, by itself, fully describes agreement between paired app and weighed measurements. A direct assessment of agreement may also require paired differences or other agreement summaries, but the registry does not report such results or explain the planned analysis.
The endpoint’s setting and timeframe delimit what it can address: energy estimation for a simulated meal measured in laboratory conditions on one day. The record does not report the mean, standard deviation, number with evaluable paired measurements, or an uncertainty interval. It therefore identifies what was intended to be measured, but does not provide the numerical evidence needed to judge the observed validity or its precision.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a pilot study with 15 enrolled participants and a primary continuous outcome comparing PortionSize measurements with weighed values. It does not report a numerical summary for that outcome, a confidence interval, a test statistic, or an analysis result. The validity question is therefore identifiable, but its empirical answer cannot be recovered from the registry record.
A mean and standard deviation are named as the endpoint’s summary measures. The mean would describe the average energy estimate or reference value, depending on the group being summarized; the standard deviation would describe variability among measurements. To interpret validity, the crucial information would include how app estimates differed from their paired weighed values. The registry record does not provide those values, their direction, or their spread. It would be inappropriate to infer close agreement, systematic overestimation, or systematic underestimation.
General statistical explanation: a confidence interval expresses uncertainty around an estimated quantity under the assumptions of the analysis. Its width depends on the data and method, and it helps distinguish a relatively precise estimate from one that remains uncertain. No confidence interval is reported for the primary outcome in this record, so precision cannot be quantified. A missing interval is not evidence that the estimate is precise or imprecise; it means that the relevant uncertainty information is unavailable in the registry record.
The stated objective also includes reliability and perceived participant satisfaction, but numerical findings for these aims are not reported. Validity, reliability, and satisfaction should not be treated as interchangeable outcomes. A comparison against a criterion measurement addresses agreement with that reference under specified conditions. Reliability would require evidence about consistency, and satisfaction would require reported participant responses. The record does not describe the measures or results for those questions.
The registry lists 15 participants in the Study Cohort and reports 0 serious adverse events, 0 other adverse events, and 0 deaths. These are counts in the registry’s safety record, not measures of app-estimation accuracy. They do not supply missing endpoint results or establish that every possible event was captured under all circumstances.
Overall, the posted information supports a description of the intended laboratory validation task and the recorded safety counts. It does not support a conclusion about how well PortionSize estimated energy intake, how consistent estimates were, or how participants rated the app. Any interpretation of effect size or statistical significance would require results not reported in the registry record.
9. Statistical Methods Explained
What does a mean and standard deviation describe?
The primary endpoint is continuous and measured in kcal. A mean is a measure of the center of a set of observations: it represents the average, while the standard deviation describes how dispersed individual observations are around that average. These summaries can describe app estimates, weighed values, or paired differences, but the registry does not specify which summary values were reported or provide the values themselves. A mean and standard deviation alone would not show whether individual app estimates agreed closely with the criterion measurements.
General statistical explanation: summary statistics compress a set of observations into a small number of quantities. That can be useful for orientation, but interpretation depends on the measurement structure. In a validation study, paired measurements from the same meal or participant are related. Treating them as unrelated groups can discard that pairing. The registry says the app measurements were compared with weighed values, but does not report the analysis method, whether the data were analyzed as pairs, or any estimated difference.
What does validation against a criterion mean?
The registry identifies weighed values as the criterion measure. In general, a criterion comparison asks how an index measurement corresponds to a reference measurement regarded as the benchmark for the specific assessment. For this study, the index measurement is from PortionSize and the reference is the weighed value in laboratory conditions. Such a comparison is specific to the measurement task and setting. It does not automatically establish performance for other meals, settings, or user groups.
Agreement and association are related but different ideas. Two measurements can move together while still differing systematically; conversely, a small average difference does not guarantee that every individual pair is close. A full interpretation may therefore consider the average paired difference and the distribution of differences, alongside any association measure. These are general analytical considerations, not claims about what this study found. The registry record does not report which agreement statistics, if any, were calculated.
What can be said about precision?
General statistical explanation: an estimate is more informative when its uncertainty is also reported. A confidence interval gives a range of values compatible with the data and analysis assumptions at the stated confidence level. Its interpretation depends on the quantity being estimated and the method used. The registry record provides no confidence interval for the primary measure and no numerical outcome summary from which to assess precision. No uncertainty range should be inferred from enrollment alone.
Standard deviation and standard error answer different questions. Standard deviation describes variation among observations; standard error describes uncertainty in an estimated summary under a statistical model. The endpoint lists standard deviation, but the record does not provide its value or state that a standard error was used. The distinction matters because a measure of participant-to-participant variability is not itself an interval for the average.
How should planning calculations be read?
General statistical explanation: a sample-size calculation is a planning exercise that relates a chosen effect, variability assumptions, significance level, allocation, and target power to a proposed number of participants or events. The registry’s planning framework specifies a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and effects defined as stated fractions of an observed effect. It also distinguishes participants per arm for ordinary outcomes from total events for time-to-event outcomes. Those assumptions describe an illustrative framework, not the actual design of this study, which is recorded as a Study Cohort and has no stated allocation.
The record does not include numerical planning results or the observed effect value. Consequently, no participant count from such an illustration can be interpreted as the study’s enrollment target, an observed power, or evidence that the pilot was adequately sized. Planning illustrations are conditional on their assumptions and do not replace reported uncertainty from the actual outcome analysis. The registry does not report the study’s own sample-size justification.
There are no statistical analyses listed for the outcomes in the registry. The analysis methods, handling of paired observations, missing measurements, and any adjustment for multiple outcomes are not reported in the registry record. These omissions prevent a detailed assessment of model assumptions or reproducibility. They also mean that general statistical concepts can clarify what the named endpoint would ordinarily require, but cannot fill in unreported methods or results.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists two outcome measures and 0 analyses. It names validity, reliability, and participant satisfaction in the study objective, while the primary outcome description focuses on validity of energy-intake estimation. The record does not explain how the two listed measures relate to those aims, identify any secondary endpoint hierarchy, or report how multiple outcomes were handled statistically.
General statistical explanation: when several outcomes or tests are examined, the chance of at least one apparently unusual result can increase if each is interpreted separately without a prespecified approach. A multiplicity strategy may define a primary outcome, adjust inference, or treat secondary findings as exploratory. The registry record does not report such a strategy, so no claim can be made about adjustment, prioritization, or confirmatory status beyond the outcome identified as primary.
Missing-data methods are also not reported in the registry record. The record gives enrollment of 15, but does not state how many participants contributed evaluable app and weighed measurements, whether any measurements were missing, or how incomplete pairs were handled. Enrollment should not be assumed to equal the analysis population. The analysis population definition, exclusions, and reasons for missing observations are not reported.
These gaps matter because the amount and pattern of missing data can affect both the analysis and its interpretation. General statistical explanation: if missingness is related to participant characteristics or measurement difficulty, results among observed measurements may differ from results that would have been obtained with complete data. That is a general concern, not evidence that missing data occurred in this study. Without a reported flow or analysis population, the registry record does not establish whether this issue arose.
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 |
|---|---|---|---|
| Study Cohort | 0 | 15 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Study Cohort | 0 of 15 |
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 |
|---|---|
| Study Cohort | 0 of 15 |
The registry safety record lists the Study Cohort with 15 participants at risk for serious events and 0 affected by serious adverse events. It also lists 15 at risk for other adverse events and 0 affected. The death count is 0. These figures describe the events recorded for the cohort; they are separate from the primary endpoint, which concerns energy-intake estimation.
General statistical explanation: a zero count means that no events of that category were recorded among the participants represented in that safety summary. It does not prove that an event is impossible, and it does not by itself provide a precise estimate of the underlying event frequency. The interpretation depends on how events were defined, collected, and attributed, details that are not reported in the registry record.
The registry does not list serious adverse-event terms. The zero counts should not be read as a measure of measurement validity, app accuracy, reliability, or participant satisfaction. They also do not establish the absence of every possible problem outside the recorded categories. No treatment comparison is represented by these safety figures: the registry identifies a Study Cohort, not a randomized control contrast.
12. What the Result Does, and Does Not, Mean
The record establishes that the study was a completed pilot with enrollment of 15 participants and a laboratory comparison of PortionSize measurements with weighed values. Its primary endpoint was a continuous energy-intake measure in kcal for one simulated meal collected on one day. Those details define the intended scope of the validity assessment.
What the record does not establish is the app’s observed accuracy. No mean, standard deviation, paired difference, confidence interval, or analysis result for the primary endpoint is reported. There is therefore no basis in the registry record for saying whether estimates tended to be higher or lower than weighed values, how variable the differences were, or how precisely any effect was estimated. The objective’s mention of reliability and perceived satisfaction does not substitute for their measurement results.
General statistical explanation: evidence from a pilot is often used to characterize feasibility or inform later study planning, but that general role does not determine what this particular study found. The registry does not report a protocol rationale or explain whether the study was designed primarily for feasibility, measurement validation, or another purpose beyond the stated preliminary aims. Nor does it report a sample-size justification for the actual study.
The record should not be read as a randomized comparison of two groups. Allocation is not stated, and the safety results are for a Study Cohort. A separate two-arm planning framework, where applicable, is an illustrative calculation rather than evidence of an actual comparator arm. The app-versus-weighed comparison is a measurement comparison, not a treatment-effect estimate.
Thus, the posted information describes a question and a measurement setting, but not a numerical answer to that question. It supports reporting the registered design and safety counts while leaving validity, reliability, satisfaction, and uncertainty unresolved. Further interpretation would require outcome results and analysis details that are not reported in the registry record.
13. Why This Trial Matters Statistically
This study is statistically interesting because it poses a measurement-validation question rather than a conventional comparison of assigned treatments. The app measurement is compared with a criterion value from weighing, and the primary endpoint is continuous energy intake in kcal. That structure makes the pairing and the way agreement is summarized central to interpretation.
General statistical explanation: a validation result is most useful when it describes both the average tendency of a measurement and how individual measurements vary around the reference. A single average can conceal spread or systematic patterns, while an association alone does not necessarily establish agreement. The registry’s description identifies the criterion comparison but does not report the statistics used to characterize it. This makes clear why an endpoint title and summary type are not enough to assess measurement performance.
The pilot also illustrates the distinction between an objective and a reported result. The objective includes preliminary validity, reliability, and perceived satisfaction, but numerical analyses are not listed. Each aim calls for outcome information appropriate to its question; one cannot infer one dimension from another. The record also demonstrates why enrollment does not alone reveal precision: uncertainty depends on observed data and analysis, neither of which is numerically reported for the primary outcome.
Finally, planning calculations need to match the design they are intended to inform. A framework assuming equal allocation between two arms does not describe a cohort-based criterion comparison when allocation is not stated. Such calculations can be useful as conditional illustrations, but they are not observed power and do not fill in an absent outcome analysis. The statistical importance of this record lies in recognizing the structure of the question and the limits imposed by the missing numerical results.
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 registry record provides a narrow description of the primary measurement task: one simulated meal collected on one day in laboratory conditions. It does not report the meal’s characteristics, the app-use procedure, or whether participants had prior experience with the app. These details would help readers understand the conditions under which estimates were made, but are not reported in the registry record.
The participant description is limited to enrollment of 15 and the condition Dietary Habits. Further demographic or clinical characteristics, eligibility criteria, recruitment methods, and participant flow are not reported. The registry also does not state how many participants had complete paired measurements. Therefore, the enrolled count cannot be treated as the number analyzed for the primary outcome.
Although the objective mentions reliability and satisfaction, the record does not describe the corresponding measures or results. It is not possible to determine whether these aims were assessed, how they were defined, or what participants reported. The registry lists two outcome measures but 0 analyses.
The primary endpoint is described as a mean with standard deviation, but no numerical summaries or uncertainty measures are reported. The analysis method, treatment of paired data, missing-data approach, analysis population, and multiplicity handling are not reported in the registry record. The record also does not report a study-specific sample-size justification or interim analysis plan. These limitations constrain assessment of both the magnitude and precision of any observed validity result, and of how the findings might apply beyond the laboratory task.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: The PortionSize Smartphone App Pilot (PS Pilot) — NCT04494971.
- Registry record last updated 2024-11-19; status last verified 2024-10.
- Results first posted 2024-10-15.
- 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 PortionSize Smartphone App Pilot (PS Pilot), sponsored by Pennington Biomedical Research Center, is listed as completed. The registry gives enrollment of 15, a start date of 2020-08-31, and a primary completion date of 2020-11-20. Dietary Habits is the listed condition.
The primary endpoint concerns validity of energy-intake estimation in kcal, comparing PortionSize measurements with weighed values in laboratory conditions for one simulated meal collected on one day. The endpoint is specified as a mean with standard deviation. The study objective also mentions preliminary reliability and perceived participant satisfaction.
The registry lists two outcome measures and 0 analyses. It does not report numerical primary results, analysis details, or findings for reliability and satisfaction. The safety record lists 0 serious adverse events, 0 other adverse events, and 0 deaths among the Study Cohort. Accordingly, the record defines the study question and its setting but does not provide a numerical estimate of app validity or its precision.