Narrative Visualization for Breast Cancer Survivors' Physical Activity: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Narrative Visualization for Breast Cancer Survivors' Physical Activity (NCT03612596), a randomized na study. The primary outcome is Percentage of Daily Workbook Entries Completed.

2. Clinical Question

The registry describes a randomized, parallel-group study with single masking. It does not identify who was masked. The intervention combines materials and activities, so the study question concerns the package as implemented rather than the isolated effect of any single scrapbook component. The secondary outcomes include physical activity measured with daily steps and measures of regulation, psychological needs, and exercise identity. The posted results include some, but not all, of those outcome areas. The registry record does not report a formal hypothesis for each outcome or specify which secondary findings were intended to be confirmatory.

3. Trial Design

The registry describes a randomized, parallel-group behavioral study comparing narrative visualization with standard self-regulation. Both groups received a wearable activity monitor and app; the accompanying materials differed. The narrative visualization group received enhanced motivational scrapbook materials, while the standard self-regulation group received standard workbook materials. The brief description says half of participants would receive each approach. Enrollment is reported as 40, but the number analyzed is outcome-specific and should not be inferred from the enrollment figure.

The study was listed as completed, with a start date of 2018-09-01 and a primary completion date of 2021-12-30. Its stated purpose was to test feasibility and acceptability of the physical activity intervention. The record gives a single-masked designation but does not say which people involved in the study were masked. Allocation concealment, the randomization procedure, and the timing of randomization are not reported in the registry record. The phase is listed as not applicable.

The primary endpoint was assessed at 12 weeks and was analyzed only in the intervention group. The registry describes secondary physical activity outcomes as change from 0 to 12 weeks during the intervention period and change from 12 to 24 weeks during the no-intervention maintenance period. It also lists psychosocial outcomes, including intrinsic and integrated regulation, basic psychological needs, and exercise identity. The posted results include analyses for steps during the intervention period, steps during maintenance, and intrinsic regulation. Results for other outcomes are not reported in the registry record as represented in the posted endpoint information.

For the secondary continuous outcomes, the record reports two-sided t-tests. The underlying statistical analysis plan, prespecified analysis populations, handling of missing observations, and any adjustment for baseline values are not reported in the registry record. The randomized design supports a between-group comparison in principle, but the interpretation of posted estimates still depends on the available analysis sample and the methods actually used.

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.

0 - 12 Weeks

12 - 24 Weeks

Analysis population for the primary outcome, as defined in the registry: This outcome was only analyzed in the intervention group

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 Percentage of Daily Workbook Entries Completed, measured over 12 weeks.

The primary endpoint is the percentage of daily workbook entries completed out of the total possible number over 12 weeks. The registry says intervention materials were photographed at the 12-week assessment and each page was then assessed. The reported mean for the narrative visualization group is 44.0 percent, with a standard deviation of 45.0, among 20 participants. No result is reported for the standard self-regulation group; the primary outcome was analyzed only in the intervention group.

This endpoint is used to describe engagement with the workbook component of the intervention. Completion can indicate whether participants used the materials often enough to make entries, which is relevant to feasibility and acceptability. It is not a direct measure of daily steps, physical fitness, or a health outcome. Nor does the mean alone establish why entries were or were not completed. A wide standard deviation relative to the mean indicates substantial variation in observed completion percentages, but the registry does not provide the individual distribution or a confidence interval for this endpoint.

Since there is no comparator-group primary result, the endpoint cannot quantify a difference in workbook completion between the two approaches. It also cannot isolate the effect of the scrapbook from the wearable monitor, app, or other elements of the intervention package. The registry record does not report a prespecified threshold for what would count as acceptable completion, so the mean should be read descriptively rather than as meeting or failing a stated feasibility criterion.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary endpoint is a continuous percentage, and the registry reports its mean and standard deviation. A mean gives the average observed value; a standard deviation describes how dispersed individual values are around that average. Those summaries are informative but do not show the full distribution. In particular, a percentage is bounded, while a mean and standard deviation alone do not reveal whether values cluster near the bounds or are spread across the range. The registry record does not report a confidence interval, a distributional assessment, or a statistical test for the primary endpoint.

What do the secondary mean differences represent?

For each secondary comparison with posted numerical results, the recalculated estimate is the narrative visualization group mean minus the standard self-regulation group mean. A positive value therefore means the narrative visualization group had the higher mean change on the reported scale; a negative value means it had the lower mean change. The units remain those of the endpoint: steps per day for step outcomes and units on a scale for intrinsic regulation. These are unadjusted comparisons from summary statistics, not adjusted model estimates.

The recalculated intervals describe uncertainty around those unadjusted mean differences under the calculation assumptions. In general, a confidence interval gives a range of values compatible with the data and a specified statistical procedure; it is not a guarantee that the true value lies within the observed limits. The registry record does not state the confidence level for the recalculated intervals. Their breadth matters: when an interval spans substantial differences in both directions, the point estimate alone gives an incomplete picture. Here, each recalculated interval includes no difference, and each is broad enough that the posted results do not precisely determine the direction or size of a group difference.

How should the p values be read?

The registry reports two-sided t-tests for the three secondary comparisons. A two-sided test considers departures in either direction, rather than testing only whether one group has a larger mean. A p value describes how unusual the observed test result, or a more extreme one, would be under the test's null model. It is not the probability that the null hypothesis is true, and it does not measure the clinical importance of an estimate.

The recalculated p values are explicitly unadjusted and derive from posted summary statistics. They are not substitutes for the sponsor's analyses. The registry's reported p values are the study's own posted tests; the recalculated values provide a simple comparison based on the available means, standard deviations, and sample sizes. No discrepancy is flagged in the registry record. Neither set of p values resolves concerns about imprecision, missing information, or the number of outcomes examined.

What does the sample-size illustration mean?

The sample-size planning illustrations are calculations from observed effects, not the trial's original design justification and not observed power. The stated assumptions are a two-sided significance level of 0.05, equal allocation, a normal approximation, and an effect set to a stated fraction of the observed effect. The displayed values are participants per arm. Such illustrations show how strongly a planning result can depend on the effect chosen: planning for a smaller fraction of an observed effect requires a larger sample under the stated assumptions. They do not show that the trial had a particular probability of detecting an effect, and they do not establish that the observed effects are reliable planning targets. The sample-size justification for the actual trial is not reported in the registry record.

Over-dispersion is a general concern when individual observations vary more than a model assumes: standard errors can then be too small, and tests can appear more precise than warranted. The posted summaries show considerable variability for some measures, but the registry record does not describe a model that accounts for over-dispersion. The secondary comparisons are reported as t-tests, and the recalculations use those posted summary statistics rather than an alternative model.

For the step outcomes, analyzed numbers are 19 and 18 across the groups; for intrinsic regulation, they are 18 and 19. These counts differ by outcome, but the reason for each difference and the treatment of unavailable observations are not reported in the registry record. The number enrolled should not be treated as the analysis size for every endpoint. Likewise, a result based on the available observations does not by itself indicate how missing observations might have affected the estimate.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Narrative Visualization")
n   <- c(20)
m   <- c(44)
sp  <- c(45)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Narrative Visualization  20  44.000  45.000  22.939  65.061

11. Multiplicity, Missing Data and Analysis Populations

The registry record includes numerous outcome measures and analyses, while only a subset of the secondary results has numerical summaries in the endpoint information. When many outcomes are tested, the chance of obtaining one or more small p values can increase even if there are no underlying group differences. This is a general statistical issue, not evidence that any particular result is false. The registry record does not report a multiplicity adjustment, a hierarchy for testing outcomes, or a prespecified approach to interpreting the secondary outcomes as a family. The reported secondary p values should therefore be read as individual, unadjusted tests.

Missing-data methods are also not reported in the registry record. The analysis counts differ across the posted step and intrinsic-regulation outcomes, and the primary endpoint is reported only for the intervention group. The registry does not explain whether unavailable observations arose from withdrawal, incomplete measurement, ineligibility for a particular measure, or another reason. It also does not state whether analyses used all randomized participants, only participants with observed outcomes, or another population definition. No imputation method, sensitivity analysis, or missingness assumption is reported.

These omissions limit assessment of bias. If the availability of outcomes is related to participants' activity or engagement, an analysis of observed values may not represent the full randomized groups. That possibility cannot be quantified from the posted information. The trial's enrollment figure is not a replacement for endpoint-specific analysis counts, and the record does not permit a conclusion about the impact of missing observations.

The registry describes the study as randomized and single masked, but it does not identify the masked party or report allocation concealment. It also does not report a statistical analysis plan or a detailed definition of analysis populations. These are reporting limitations: they leave uncertainty about how outcomes and analyses were selected and implemented. They should be distinguished from evidence of a flaw, which cannot be established from the information recorded.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The registry reports zero serious adverse events in each group, with 20 participants at risk in each group for this safety summary. It also reports zero other adverse events in each group and zero deaths. No serious adverse event terms are listed. These figures describe the events recorded in the registry for the stated groups and at-risk counts.

A zero count in a study of this size does not establish that an intervention has no risk. It means no events of the reported category were recorded in the stated group during the period covered by the registry safety data. Rare events, events occurring outside the recorded period, or events not captured in the registry cannot be ruled out from these counts. The safety record does not provide event narratives, severity details beyond the serious-event category, or information about how events were collected and adjudicated. The registry record also does not state the safety follow-up duration. Accordingly, the counts should be read as a limited descriptive report, not as a comparative safety analysis or a general safety conclusion.

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

The posted results describe several different questions. The primary endpoint reports how often workbook entries were completed within the narrative visualization group. The secondary comparisons describe differences between groups in selected changes in daily steps and intrinsic regulation. These outcomes are related to the study's feasibility and physical-activity focus, but they are not interchangeable. Workbook completion is not a direct measure of physical activity, and a change in a scale score is not a measure of workbook use.

The secondary estimates are accompanied by wide intervals that include no difference. This means the available data do not precisely locate the between-group contrasts. It does not show that the approaches are equivalent, nor does it establish that the observed estimates represent the true effects. A nonsignificant p value is not proof of no effect, and a small point estimate is not by itself proof of no meaningful difference. The registry does not report a threshold for a practically important difference on these outcomes.

The trial's stated aim was feasibility and acceptability, but the registry record does not report prespecified criteria for deciding whether either was adequate. The primary completion mean can inform a descriptive discussion of workbook engagement; without a comparator result, threshold, or more detailed distribution, it cannot establish comparative acceptability. The secondary outcomes may offer additional signals about activity and related constructs, but they do not replace a formal feasibility assessment.

The results should not be interpreted as medical advice or as a determination that either intervention works or does not work. They are limited to the reported outcomes, analysis samples, and comparisons. The unreported statistical plan, missing-data handling, and multiplicity procedures add uncertainty. Further conclusions would require information beyond what the registry record reports, including fuller outcome reporting and transparent definitions of the analyses.

14. Why This Trial Matters Statistically

This study is statistically informative because it illustrates how a trial's primary endpoint can answer a narrower question than its broader intervention goal. Workbook completion is a measure of engagement with intervention materials, while daily steps are a behavioral outcome. Keeping those estimands separate prevents a descriptive feasibility measure from being mistaken for evidence of a physical-activity difference.

It also illustrates why a point estimate should be read alongside its uncertainty. The secondary mean differences are accompanied by broad intervals, so the data do not precisely distinguish among a range of possible group contrasts. The p values alone would conceal that uncertainty. Reading estimates, intervals, and sample sizes together gives a more calibrated account than labeling results only as statistically significant or not significant.

The outcome-specific analysis counts and limited set of posted secondary results matter as well. Enrollment does not guarantee that every enrolled participant contributes to every endpoint, and without missing-data methods it is difficult to assess whether the observed analyses represent the randomized groups. With multiple outcomes, unadjusted tests also require cautious interpretation. These are common challenges in behavioral intervention research, where intervention engagement, activity measures, and psychosocial constructs may all be relevant but answer different questions.

Finally, planning illustrations based on observed effects are not the same as the original sample-size rationale or observed power. They depend on assumptions and on estimates that may be unstable in a small study. Treating such calculations as planning scenarios, rather than as evidence about the trial's adequacy or likelihood of success, keeps the statistical interpretation aligned with what the registry actually reports.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

Several limitations specific to this record affect interpretation. The primary endpoint is available only for the narrative visualization group, so it cannot compare workbook completion across the randomized approaches. Its mean and standard deviation are reported without an interval, distribution, or prespecified criterion for acceptable completion. The result therefore remains descriptive.

The secondary analyses use outcome-specific numbers of participants, and the record does not explain why those counts differ or how missing observations were handled. The estimates may be affected by which participants contributed data, but the direction or magnitude of any such effect cannot be determined. The registry does not report a detailed analysis population or sensitivity analyses.

Only some of the listed secondary outcome areas have numerical results in the endpoint information. Without results for the remaining measures, the available findings may not represent the full set of outcomes collected. The record also does not report adjustment for multiple comparisons or a hierarchy that would clarify the relative evidential status of the secondary tests.

The reported trial design information is limited: the registry does not describe the randomization procedure, allocation concealment, who was masked, or the statistical analysis plan. It does not report a sample-size justification, the primary endpoint's inferential procedure, or a comparative primary result. The sample-size illustrations are based on observed effects and should not be mistaken for the original design assumptions. These reporting gaps constrain assessment of bias, precision, and analysis choices, without proving that any particular procedure was inappropriate.

Finally, the reported outcomes and safety counts are bounded by what the registry records. The safety summary gives event counts but not detailed collection methods or follow-up duration. The study's feasibility and acceptability purpose is not accompanied by reported decision thresholds. Conclusions should remain limited to the observed summaries and the information documented in the registry.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Narrative Visualization for Breast Cancer Survivors' Physical Activity — NCT03612596.
• Registry record last updated 2023-06-09; status last verified 2023-06.
• Results first posted 2023-06-09.
• 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.

19. Record Summary

NCT03612596 is a completed randomized, single-masked, parallel-group behavioral study titled “Narrative Visualization for Breast Cancer Survivors' Physical Activity.” It compared narrative visualization materials with standard self-regulation materials, with a wearable activity monitor and app in both groups. Enrollment is reported as 40, and the study's stated purpose was to assess feasibility and acceptability.

The primary outcome was the percentage of possible daily workbook entries completed over 12 weeks, analyzed only in the intervention group. Posted secondary comparisons cover changes in daily steps during the intervention and maintenance periods and change in intrinsic regulation. The registry reports no serious adverse events, other adverse events, or deaths in either group in its safety summary.

The secondary estimates are imprecise, and the primary outcome has no comparator-group result. The registry record does not report key details about missing-data handling, multiplicity, analysis populations, or the statistical analysis plan. Results should therefore be interpreted as limited descriptive and comparative evidence rather than definitive conclusions about intervention effects.