Change in Knowledge After Receiving Personal Air Pollution Results: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Change in Knowledge After Receiving Personal Air Pollution Results (NCT05160948), a registered phase not stated study. The primary outcome is Report-Back Pre/Post Survey.

2. Clinical Question

The study asks whether receiving personal air-monitoring results is followed by a change in participants’ and caregivers’ reported understanding of air pollution and beliefs about science and research. The survey was planned at baseline and again within 30 days after participants received their individual monitoring results. The registry describes this as a pre/post assessment, not as a randomized comparison of report-back against a control condition.

The study’s rationale is that individualized exposure information may help participants recognize how exposure varies with their activities and surroundings. The investigators describe report-back as potentially informative and believe it may increase awareness, identify times or locations of elevated exposure, and inform behavior. Those statements describe the rationale, not findings from the primary survey. The registry record does not report the observed score changes or the statistical evidence for them.

3. Trial Design

The registry identifies this as a completed study titled “Change in Knowledge After Receiving Personal Air Pollution Results.” Its official title describes an assessment of changes in knowledge, behavior, and attitude after personal air-monitoring results are received. The condition is Environmental Exposure, and the intervention is categorized as an informational report. The sponsor is Children’s Hospital Medical Center, Cincinnati.

The record lists enrollment of 105 and gives a study start date of 2021-11-10 and a primary completion date of 2022-11-10. These are registry entries; they do not indicate how many participants contributed data to each survey question. The record does not state the allocation method. It explicitly cautions that the arms are not a like-for-like control comparison, so an arm contrast should not be read as the effect of report-back against a comparable untreated group.

The primary outcome is described as a report-back pre/post survey. EcoMAPPE participants and caregivers were to answer questions about understanding air pollution and beliefs about science and research before and after receiving individual monitoring results. The post-report survey timeframe is within 30 days. The intervention described is the report itself; the record does not describe a separate intervention protocol or a control intervention.

The registry classification is “other,” rather than a conventional randomized trial design. The record does not report a protocol description of randomization, masking, or a controlled assignment process. It also does not report a design rationale or sample-size justification. The study’s completed status and enrollment are not substitutes for outcome results: the registry record does not give the primary survey’s observed scores or estimates of change.

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

Analysis population for the primary outcome, as defined in the registry: Certain questions were pre-specified to be collected only from caregivers, therefore, Adolescent Arms/Groups did not have data collected for these questions (0 participants analyzed)

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.

6. Primary Endpoint

The registry lists the primary outcome as Report-Back Pre/Post Survey, measured over Baseline and within 30 days.

The primary endpoint is the mean score on a scale for the “Report-Back Pre/Post Survey,” with the full range identified as the dispersion measure. The survey is intended to assess understanding of air pollution and beliefs about science and research before report-back and within 30 days after participants receive their personal monitoring results.

The description says the questions use a Likert response scale from 1 to 5, with response anchors ranging from strongly disagree to strongly agree and a neutral midpoint. In general, these responses capture the direction and degree of agreement with a statement. A mean can provide a compact description of responses across participants, while the full range indicates the spread from the lowest to highest observed scores. The registry record does not report the actual means or ranges.

The endpoint is relevant to the study’s stated question because it focuses on participants’ understanding and beliefs, rather than measuring air pollution itself or a health outcome. However, the record does not explain how individual survey items were combined, whether scores were calculated separately for different topics, or how missing answers affected a score. It does not report evidence about the survey’s measurement properties. These details matter when interpreting what a mean score represents and whether a change reflects a consistent shift across questions or differing responses to particular items.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies a mean score and a full range for the primary survey outcome, but it does not report the statistical method used to compare baseline and post-report responses. The distinction matters: an endpoint description tells readers what was intended to be measured, while an analysis method explains how the observed data were used to estimate change and quantify uncertainty.

What does a pre/post comparison describe?

In general, a pre/post analysis compares measurements taken at different times. If the same participant contributes responses at both times, an analysis can use the within-participant change and account for the fact that two responses from one person are related. That approach differs from comparing two independent groups, where observations from one group are not paired with observations from the other. The registry describes a pre/post survey but does not specify whether the primary analysis used paired observations, how participants with only one survey were handled, or whether the analysis was instead based on group-level means.

A simple difference between two reported means would describe a change in the mean score, but the interpretation depends on who contributed to each mean and on the scoring rules. If the sets of respondents differ over time, a change in group means can reflect both response changes and a change in respondent composition. The registry record does not report the analysis population at each time point or a rule for matching surveys. It therefore does not establish how those issues were addressed.

What does the mean and full range tell readers?

In general, a mean summarizes responses with a single measure of central tendency. The full range describes the lowest and highest recorded values, but it does not show how responses are distributed between those endpoints. Two sets of responses can share a mean and range yet have different patterns of concentration or variability. Additional summaries, such as the distribution of responses or an appropriate measure of spread, can help readers understand that pattern; the registry record does not report such details for this endpoint.

The survey uses ordered agreement categories, from strongly disagree through a neutral response to strongly agree. In general, an individual Likert item is ordinal: its categories have an order, but the spacing between adjacent categories is not necessarily equal. A mean treats the response scale as if those steps can be averaged numerically. That may be a useful summary, but interpretation depends on the scoring plan and the way items are combined. The registry record does not state whether the reported score is an individual item, a composite, or another construction, nor does it describe rules for incomplete item responses.

Why does uncertainty matter?

In general, an estimate alone does not show how precisely the study measured a change. A confidence interval expresses uncertainty around an estimate under the analysis assumptions. It helps readers distinguish a comparatively precise estimate from one compatible with a broad range of possible changes. The registry record does not report an estimate or confidence interval for the primary outcome, so precision cannot be assessed.

A hypothesis test may be used to evaluate compatibility between the observed data and a specified null hypothesis. A p-value is not the probability that the null hypothesis is true, nor does it measure the size or importance of a change. It is most informative alongside an effect estimate, an interval, the analysis population, and a description of the model. The registry record does not report a primary endpoint test or its assumptions.

What assumptions are stated for planning?

The record describes planning illustrations using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It states that the effect to detect is a specified fraction of the observed effect. These are planning assumptions, not a description of the study’s actual allocation or primary analysis. The record also characterizes the calculations as illustrations based on the observed effect, not as the study’s own design justification. Such illustrations are not observed power and cannot replace a report of the outcome estimate and its uncertainty.

In general, a normal approximation relies on the sampling distribution being adequately represented by a normal model for the purpose at hand. If survey outcomes are strongly bounded, skewed, or concentrated in a few response categories, the approximation may not describe their uncertainty well. Whether that concern applies depends on the observed responses and the analysis; those details are not reported in the registry record. The equal-allocation assumption likewise should not be mistaken for evidence that the actual study assigned participants equally between arms.

What analysis details remain unknown?

The registry record does not report the statistical model, whether the outcome was analyzed as a continuous score or as ordered categories, the treatment of repeated responses, or any adjustment for covariates. It does not report a method for handling missing responses or explain whether analyses were prespecified. These omissions prevent readers from checking whether the analysis matched the data structure and question. They also mean that the assumptions behind any reported estimate cannot be evaluated from this record alone.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome description covers questions about understanding air pollution and beliefs about science and research. The registry lists one outcome measure and one analysis, but does not describe how many survey items contributed to the score, whether separate item-level results were examined, or whether any other outcomes were tested. A multiplicity strategy—such as prioritizing a prespecified primary comparison or adjusting inference across multiple tests—is not reported in the registry record. Without that information, the scope of statistical testing and the interpretation of any p-values cannot be assessed.

Missing-data methods are also not reported in the registry record. The record does not explain how incomplete surveys, unanswered items, or participants without responses at both time points were handled. In general, missingness can affect both the number and the characteristics of respondents represented in an estimate. If the likelihood of completing a survey is related to a participant’s responses or circumstances, a complete-response analysis may not represent all enrolled participants. The registry does not provide enough detail to judge whether this concern arose or how it was addressed.

There is one specific population qualification: certain questions were pre-specified for caregivers only. Adolescent arms or groups had no data collected for those questions, with 0 participants analyzed. This is a planned restriction for those items, not evidence that responses were missing at random or that all other questions had complete data. The registry record does not report the number analyzed for each other question or identify the analysis population for the primary score.

The record also does not state an intention-to-treat or other analysis-population definition. Because allocation is not stated and the arms are not described as a like-for-like control comparison, standard assumptions associated with randomized-group analyses cannot be inferred. Readers would need participant flow, item-level completeness, scoring rules, and analysis-population definitions to evaluate how exclusions or missing responses might affect the results.

11. What the Result Does, and Does Not, Mean

The study addresses an important measurement and communication question: whether people’s reported knowledge and beliefs differ after they receive personal air-monitoring results. Its rationale is that personal measurements may be easier to connect to an individual’s activities and surroundings than less individualized exposure information. The investigators describe possible benefits of report-back, but these are motivations for conducting the study, not demonstrated effects.

The registry record does not report the primary survey scores or an estimate of pre/post change. It therefore does not establish whether responses changed, how large any change was, or how precisely it was measured. It also does not provide evidence about whether report-back changed behavior or attitudes beyond the survey topics described. The official title includes behavior and attitude, while the primary outcome description focuses on understanding and beliefs; the record does not report additional outcome results.

Even if a pre/post difference were available, it would describe change over time among the analyzed respondents. Without a comparable control condition and a stated allocation method, that change alone would not isolate the effect of receiving the report from other explanations. The registry’s caution that the arms are not a like-for-like control comparison is especially relevant to interpretation. A statistical association between report-back and changed responses would not, on its own, establish that report-back caused those changes.

The survey score is also a measure of reported responses, not a direct measurement of exposure, health, or behavior. A mean score can help summarize answers, but its meaning depends on the question wording, scoring method, and pattern of responses. The registry record does not report those details sufficiently to establish how a score change should be interpreted in practical terms.

Accordingly, the record supports describing the study question and its planned survey timing, but not drawing a conclusion about the direction or strength of the primary result. No medical advice or treatment conclusion follows from the registry information. A complete interpretation would require the observed outcome values, an uncertainty estimate, analysis details, and information about who contributed data at each time point.

12. Why This Trial Matters Statistically

Personal exposure can vary with where people go and what they do, as the study rationale notes. Research that returns individualized measurements therefore raises questions not only about measurement, but also about how recipients understand and use the information. Assessing responses before and after report-back is one way to study that communication process. The registry describes this purpose, while the absence of posted primary results means the size and direction of any measured change remain unknown.

Statistically, the study highlights the importance of aligning the outcome with the question. A survey about knowledge and beliefs captures reported understanding and attitudes; it does not directly measure exposure or establish a health effect. Clear scoring rules and respondent definitions are essential when a study uses mean scores from agreement-scale questions. The registry identifies the broad outcome and scale but does not describe enough scoring detail to evaluate the construct represented by the score.

The design also illustrates why a pre/post pattern and a causal effect are not interchangeable. Repeated measurements can describe change, but a credible causal interpretation depends on design and analysis details, including an appropriate comparison and how participants contribute data over time. The registry explicitly says that the arms are not a like-for-like control comparison and does not state allocation. That limits what can be inferred from any arm-based contrast.

Finally, completeness and precision are central to interpreting survey research. Caregiver-only questions were not collected from adolescent arms or groups, and the record does not describe other missing-data handling or provide outcome uncertainty. Reporting respondent flow, score construction, analysis populations, and estimates with uncertainty would help readers distinguish a meaningful pattern from an imprecise or composition-sensitive one. These are general statistical considerations; the registry does not establish how they were handled in this study.

13. 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 most important limitation for interpreting the primary outcome is that the registry record does not report the observed survey results. Without the baseline and post-report scores, an estimate of change, and its uncertainty, readers cannot evaluate direction, magnitude, or precision. Completed status and enrollment do not fill that gap.

The record gives limited detail about the survey instrument. It describes the Likert response anchors and the broad topics but does not explain the number or wording of items, the scoring rule, whether items were combined, or how incomplete answers were treated. It also does not report measurement validation or whether the same questions and scoring procedures were applied at both time points. This makes it difficult to determine exactly what a mean score represents.

The planned comparison is pre/post, and the registry says allocation is not stated and the arms are not a like-for-like control comparison. Consequently, any change over time would not by itself separate report-back effects from other influences. The record does not describe a control condition, the timing of other study activities, or methods for addressing alternative explanations.

Population and missing-data information is incomplete. The record identifies caregiver-only questions that were not collected for adolescent arms or groups, but it does not report the analysis population for the remaining questions, survey completion at each time point, or missing-data procedures. Enrollment of 105 should not be interpreted as the number contributing to every endpoint.

Finally, statistical methods are not described sufficiently to evaluate model choice, repeated-measure handling, covariate adjustment, multiplicity, or assumptions. The record does not provide a sample-size rationale for the study. Planning illustrations are not a substitute for that rationale or for the outcome analysis.

14. Related Tutorials

15. Related Statistical Calculators

16. Sources

• ClinicalTrials.gov: Change in Knowledge After Receiving Personal Air Pollution Results — NCT05160948.
• Registry record last updated 2026-07-31; status last verified 2026-07.
• Results first posted 2026-07-31.
• 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.

17. Record Summary

The registry describes a completed study of an informational report containing individual personal air-monitoring results. It planned to assess EcoMAPPE participants’ and caregivers’ understanding of air pollution and beliefs about science and research at baseline and within 30 days after report-back. Enrollment is listed as 105; the study dates are 2021-11-10 to 2022-11-10, with primary completion on 2022-11-10.

The primary measure is a mean survey score with the full range reported as the dispersion measure. Certain questions were reserved for caregivers, and adolescent arms or groups had 0 participants analyzed for those questions. The registry notes that allocation is not stated and that arms are not a like-for-like control comparison.

The registry record does not report primary outcome values, estimates of change, uncertainty, or the statistical analysis used. It also does not report missing-data methods, score construction, or a study-specific sample-size justification. Therefore, the record describes the question and planned measurement but does not allow assessment of the observed primary result.