MOtiVating Endometrial Cancer Survivors With Activity Monitors and Tailored Feedback: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for MOtiVating Endometrial Cancer Survivors With Activity Monitors and Tailored Feedback (NCT03820024), a randomized na study. The primary outcome is Change in Steps in Endometrial Cancer Survivors During 12 Week Intervention.

2. Clinical Question

The registry describes a behavioral intervention intended to encourage physical activity among endometrial cancer survivors. The primary outcome is change in steps recorded by a fitness tracker at week 1 and week 13. The brief summary states a hypothesis that women receiving feedback would increase step counts from baseline more than 2,000 steps compared with women in the non-intervention arm. That is the stated hypothesis, not a result. The posted arm means are 1037.0 for tailored feedback messages and 309.0 for no messages. The registry’s listed mean difference is -728.0 for the comparison labeled No Messages; its direction is consistent with subtracting the tailored-feedback mean from the no-messages mean. These estimates describe the posted outcome and do not by themselves establish why the groups differed or how reliably the result would generalize beyond the participants studied.

3. Trial Design

MOVES is described as a randomized, single-masked, parallel-group trial of tailored feedback messages for endometrial cancer survivors. The intervention is behavioral. Participants assigned to the feedback arm were to receive one message per week during the 3-month study period. Messages were described as encouragement and reminders based on the CHART algorithm. Participants in the comparator arm received no feedback messages. The registry does not identify who was masked, so the meaning of single masking in practice is not reported in the registry record.

The registry lists enrollment of 39, while the posted outcome results list 18 participants in each arm. The brief summary says investigators planned to enroll 36 women, with 18 in each arm. The record does not explain the difference between planned enrollment and registry enrollment, or how many randomized participants contributed data to the reported outcome. It also does not state whether everyone assigned to an arm was included in the analysis.

The primary outcome is titled “Change in Steps in Endometrial Cancer Survivors During 12 Week Intervention.” Its timeframe is listed as 13 weeks, and its description identifies tracker recordings at week 1 and week 13. The study status is completed. The registry lists a start date of 2018-09-28 and a primary completion date of 2019-12-23. The phase is listed as NA.

The record does not report the original statistical analysis plan, the method used to handle repeated or missing tracker readings, or whether the outcome analysis followed randomized assignment. Details about recruitment, adherence, and the masking procedure are also not reported in the registry record. Those omissions limit how fully the posted group comparison can be evaluated.

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.

Before assignment: Thirty-nine participants were consented

Overall Study

Reasons for not completing this period:

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 Change in Steps in Endometrial Cancer Survivors During 12 Week Intervention, measured over 13 weeks.

The primary endpoint is change in steps, a continuous measure of physical activity recorded on a fitness tracker. The registry describes recordings at week 1 and week 13, with a 13-week timeframe. The endpoint title refers to a 12-week intervention. The record does not explain the relationship between that title and the stated timeframe.

Change in steps is relevant to the stated study question because the intervention was designed to encourage physical activity, and step counts offer a numerical measure that can be compared between randomized groups. A mean summarizes the average outcome for each arm. The posted mean is 1037.0 for tailored feedback messages and 309.0 for no messages. The registry labels the outcome as a mean and identifies standard error as its dispersion measure.

In general, a continuous endpoint can retain more information than converting participants into broad categories, because the measured values contribute to the group summaries. However, step counts may vary substantially between people and over time. The registry does not describe how tracker readings were processed, whether the change was calculated for each participant before averaging, or how incomplete recordings were handled. Those details matter when interpreting a mean change and its uncertainty. The registry also does not report a separate endpoint definition for baseline beyond identifying week 1 as the first recording.

7. Results Posted in the Registry

• No Messages: mean 309.00 versus 1,037 on control; difference -728.00 (95% CI -728.78 to -727.22), standardized effect d = -605.91; z-test p = <0.001.

8. Statistical Interpretation

9. Statistical Methods Explained

The outcome is continuous and is summarized as a mean. In general, a mean is the arithmetic average of measured values and gives a central summary on the outcome’s original scale. Here, the scale is change in steps. The posted arm means are 1037.0 for tailored feedback messages and 309.0 for no messages. The record identifies standard error as the dispersion measure, but it does not explain the precise calculation of either the arm means or their standard errors.

In general, a standard error describes uncertainty in an estimated quantity, such as a mean, rather than the spread of individual participants’ measurements. It is commonly used to construct confidence intervals and conduct tests. It should not be interpreted as showing that participants’ step changes were tightly clustered. The registry does not provide a standard deviation for the outcome or a distribution of individual changes, so the variability between participants cannot be assessed from these entries alone.

The reported mean difference is -728.0, and the comparison is labeled No Messages. Considering the posted arm means, the negative sign is consistent with subtracting the tailored-feedback mean from the no-messages mean. A difference is useful because it expresses the contrast between groups on the original step scale. The confidence interval describes a range of values compatible with the reported estimate under the statistical procedure used. The registry does not describe that procedure, so its exact assumptions cannot be checked from the record.

The unadjusted p-value is <0.001. In general, a p-value measures how unusual data at least as incompatible with a specified null hypothesis would be if that hypothesis and the test’s assumptions held. It is not the probability that the null hypothesis is true, nor does it describe the size or practical importance of an effect. “Unadjusted” indicates that the reported value is not presented as adjusted for multiple comparisons. Whether other analyses were conducted, or whether any adjustment was planned, is not reported in the registry record.

The study is randomized and parallel-group, so its structure assigns participants to one of two groups for comparison. Randomization can help balance measured and unmeasured characteristics on average, but it does not guarantee balance in a small study. The registry does not report the randomization method, allocation concealment, or baseline characteristics. It also does not say whether the analysis retained participants in their assigned groups, or whether exclusions or adherence criteria were used.

Steps are count-like measurements. In general, count outcomes can have skewed distributions or variability that changes with the expected count; over-dispersion means the variability exceeds what a chosen probability model would expect. These possibilities can affect standard errors and the suitability of a statistical model. This is general statistical context, not a claim about the MOVES data. The registry does not report the distribution of step changes or a model choice, so it is not possible to tell whether such features were assessed.

The posted standardized estimate is -605.9. Standardized effects express a difference relative to a measure of variability and can be useful when outcomes use different scales. Their interpretation depends on the standardization and the quality of the variability estimate. The record lists a pooled standard deviation of 1.201, as well as standard errors of 0.02 and 0.4 for the two arms, but gives no explanation of how these quantities were obtained. The unusually large magnitude of the standardized estimate should therefore be interpreted cautiously, not as an independently verified description of a typical participant’s change.

The sample-size planning illustration uses a two-sided significance level of 0.05, equal allocation, and a normal approximation. It considers detecting 100%, 75%, and 50% of the observed effect and reports participants per arm for the power targets. These are planning calculations based on the observed effect, not a record of the trial’s original design justification. In general, smaller target effects require more information and therefore more participants to detect with a chosen power, all else equal.

The registry does not report the original sample-size assumptions, a formal statistical analysis plan, interim analyses, missing-data methods, or analysis populations. No analysis entries are posted. Consequently, the methods are limited to the statistical quantities and design labels in the record; the underlying sponsor analysis cannot be reconstructed from the available information.

10. Confidence Intervals and Precision

The reported mean difference is -728.0, with a 95% confidence interval from -728.8 to -727.2. A confidence interval expresses uncertainty around an estimate under the method used to calculate it. It is not a range containing a specified proportion of individual participants’ outcomes. The interval is narrow relative to the estimated difference and does not include zero. The associated unadjusted p-value is <0.001.

The registry does not state the confidence level explicitly alongside the comparison, nor does it describe the interval calculation in the analysis record; the interval is presented as the posted confidence interval. Its apparent precision should be considered in light of the listed arm standard errors, 0.02 and 0.4, and the absence of methodological detail. The record does not explain how those values relate to the interval or whether the mean difference was calculated from participant-level change scores.

A narrow interval can indicate that an estimate is precise under the statistical model and data used. It does not address bias, measurement quality, generalizability, or whether the model’s assumptions are suitable. Because the analysis method, missing-data handling, and distribution of individual observations are not reported in the registry record, the interval alone cannot settle those questions.

The unusually small width relative to the scale of the arm means makes clarification of the calculation particularly relevant. The record lists no discrepancy flag, but provides no detailed derivation that would allow the interval to be independently assessed. The result can be stated as posted, while avoiding a stronger claim about precision than the available analysis details support.

11. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning entries are expressed as participants per arm, not as a total number of events. The calculation assumes a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. It considers effects set at 100%, 75%, and 50% of the observed effect, with separate targets for 80% and 90% power. The entries are 1 participant per arm for each displayed effect level and each power target.

In plain language, the 80% power column gives the calculated number of participants per arm for a design intended to have an 80% chance of detecting the specified effect under the planning assumptions, if that effect and the assumed model are correct. The 90% power column uses a higher detection probability as the target. Smaller effects are harder to distinguish from random variation and generally require more participants, all else equal. The fact that the displayed values do not increase for the smaller effect levels makes these planning entries difficult to use as realistic recruitment guidance without further information about the calculation.

These values are planning illustrations derived from the observed effect, not the trial’s original design assumptions. The original sample-size justification is not reported in the registry record. This is not observed power: it does not measure the probability that the completed trial detected a true effect, and it does not change the uncertainty in the posted result. The planning calculation should be interpreted in light of the unusually large observed contrast and the limited information about its underlying analysis.

12. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = -728.000; pooled standard deviation σ = 1.201.
2. n = 2 × (1.96 + 0.842)² × 1.201² / -728.000² = 0.0, rounded up to 1 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- -728                      # observed difference in means
sigma <- 1.20149906367005                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(3820024)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 1 (80% power), 1 (90% power)
 75% of observed effect: n per arm = 1 (80% power), 1 (90% power)
 50% of observed effect: n per arm = 1 (80% power), 1 (90% power)
power.t.test: 1.2 
Simulated power at n = 1 per arm: NA (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

13. Multiplicity, Missing Data and Analysis Populations

The registry lists one outcome measure and no posted secondary outcomes. It also reports no analysis entries. That does not establish that only one statistical test was conducted; the registry does not provide a complete analysis plan or a list of all analyses performed. Whether the primary comparison was designated before outcome data were examined, and whether any multiplicity adjustment was planned, is not reported in the registry record.

Multiplicity arises when several outcomes, time points, subgroups, or alternative analyses are tested. In general, testing many hypotheses can increase the chance of obtaining a small p-value even when no underlying difference exists. An analysis plan and transparent reporting of all planned and performed comparisons help readers assess that issue. The available record does not allow that assessment beyond the single posted outcome and comparison.

Missing-data handling is also not reported. The record identifies tracker readings at week 1 and week 13 but does not state whether every randomized participant posted both readings, how incomplete recordings were handled, or whether values were imputed. It does not describe exclusions, protocol deviations, or adherence-based analyses. These omissions matter because the reported mean change could depend on which participants had usable measurements and how missing observations were treated.

The registry lists 39 participants as enrolled, while the two outcome arms each list 18 participants. The brief summary describes a planned enrollment of 36 women. The record does not explain the relationship among these figures or identify the analysis population. It is therefore not possible to determine from the registry whether the outcome results represent all randomized participants, only those with complete tracker data, or another group.

Whether an intention-to-treat analysis, per-protocol analysis, or other population was used is not reported in the registry record. The original statistical plan, interim analyses, and adjustment for covariates are likewise not reported. These gaps limit interpretation of the p-value and confidence interval and prevent a full assessment of analysis choices.

14. 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 among 18 participants at risk in the tailored-feedback arm and zero among 18 at risk in the no-messages arm. Other adverse events are also listed as zero in each arm, and deaths are listed as zero in both arms. No serious adverse event terms are listed.

These figures describe the events recorded in the registry for the listed groups. They do not establish that no unwanted experiences occurred, and they cannot show whether the intervention caused or prevented an event. The record does not provide further detail about how adverse events were defined, collected, or monitored, or about the duration of safety follow-up. Counts of zero should therefore be understood as registry reporting, not as proof of absence of risk.

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

The posted results show a higher mean change in steps in the tailored-feedback arm than in the no-messages arm: 1037.0 compared with 309.0. The comparison labeled No Messages reports a mean difference of -728.0, with a confidence interval from -728.8 to -727.2 and an unadjusted p-value of <0.001. These values describe the registry’s reported group comparison on the step-change outcome.

They do not show why the groups differed. The record does not describe participant-level data, adherence to messages, missing tracker readings, or the analysis method. The listed confidence interval is very narrow relative to the outcome scale, and the registry does not explain its derivation. The standardized estimate of -605.9 is also difficult to interpret without more information about its calculation. These limitations call for caution about the degree of precision represented by the posted statistics.

The results do not establish that all participants changed in the same way, that the outcome would persist after the intervention period, or that the same result would occur in other settings or populations. The registry record describes a specific group of endometrial cancer survivors and a defined messaging intervention; it does not report long-term follow-up or outcomes beyond the posted primary measure.

The brief summary’s hypothesis refers to an increase from baseline more than 2,000 steps compared with the non-intervention arm. The posted arm means and comparison are not a reported test of that threshold. No separate result addressing it appears in the registry record. The statistical findings should not be turned into medical advice or a broad conclusion about treatment effects.

16. Why This Trial Matters Statistically

This trial illustrates how a simple behavioral intervention can be assessed with a continuous activity measure. A randomized comparison of tracker-based step change makes the statistical question concrete: how the average recorded change differed between participants offered tailored messages and those receiving no messages. The posted outcome is directly aligned with the study’s stated interest in physical activity.

It also illustrates why estimates need to be read together with the information used to produce them. The registry gives group means, standard errors, a mean difference, a confidence interval, and a p-value, but does not describe the analysis procedure or missing-data handling. The very narrow interval and the extreme standardized estimate cannot be fully appraised from the record alone. Statistical significance does not resolve those uncertainties.

The planning illustration underscores another general issue: sample-size calculations depend on the effect size and assumptions chosen. Here, the displayed planning entries are based on the observed effect and yield 1 participant per arm across the stated effect fractions and power targets. They are not the original design justification and should not be taken as evidence that such a small study would reliably detect more modest effects.

Finally, registry transparency affects statistical interpretation. Reporting the analysis population, outcome derivation, tracker-data processing, and planned comparisons would help readers understand how the published summary relates to the randomized design. The posted record offers a useful outline of the clinical question and observed results, but leaves important analytic details unresolved.

17. 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 outcome record is sparse. It identifies tracker readings at week 1 and week 13 but does not explain how participant-level change was calculated, how many readings were required, or how incomplete readings were handled. The primary outcome title refers to a 12-week intervention, while the timeframe is listed as 13 weeks; the record does not clarify that difference.

The registry reports enrollment of 39, and the brief summary describes a plan to enroll 36 women, while the outcome arms list 18 participants each. It does not explain the relation between enrollment and the outcome analysis groups. Baseline characteristics, the randomization procedure, allocation concealment, and the identity of the masked party are not reported. These gaps make it difficult to assess group comparability and the path from assignment to the posted estimates.

No original sample-size justification or complete statistical analysis plan is reported. The analysis method, treatment of missing data, analysis population, and any adjustment for covariates or multiple testing are not reported in the registry record. The unusually narrow confidence interval and extreme standardized estimate cannot be evaluated without more detail about their calculation. The record also provides no secondary outcome results or long-term outcome assessment.

The reported adverse-event counts are limited to the figures posted and are not accompanied by detailed definitions or collection methods. Overall, the record supports describing the displayed results, but not a thorough independent evaluation of the data quality or analysis decisions.

18. Related Tutorials

19. Related Statistical Calculators

20. Sources

• ClinicalTrials.gov: MOtiVating Endometrial Cancer Survivors With Activity Monitors and Tailored Feedback — NCT03820024.
• Registry record last updated 2021-07-29; status last verified 2021-07.
• Results first posted 2021-07-29.
• 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.

21. Record Summary

The MOVES trial, titled “MOtiVating Endometrial Cancer Survivors With Activity Monitors and Tailored Feedback,” is listed as a completed, randomized, single-masked, parallel-group behavioral study sponsored by UNC Lineberger Comprehensive Cancer Center. It compared weekly tailored feedback messages with no messages among endometrial cancer survivors. The registry lists enrollment of 39; the primary outcome arms list 18 participants each.

The primary outcome was change in tracker-recorded steps at week 1 and week 13. The posted means were 1037.0 for tailored feedback and 309.0 for no messages. The comparison labeled No Messages reports a mean difference of -728.0, a confidence interval from -728.8 to -727.2, and an unadjusted p-value of <0.001. No analysis entries or secondary outcome results are posted. The registry does not report key analysis details, including missing-data handling and the analysis population.