National Survey to Understand Ethical, Legal and Social Issues in Communicating to the Public About Epigenetics: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for National Survey to Understand Ethical, Legal and Social Issues in Communicating to the Public About Epigenetics (NCT07020234), a randomized na study. The primary outcome is Knowledge & Understanding of Epigenetics Information.

2. Clinical Question

3. Trial Design

This is a completed, randomized, parallel-group behavioral study, registered as NCT07020234. Its title describes a national survey about ethical, legal and social issues in communicating to the public about epigenetics. Washington University School of Medicine is listed as the sponsor. The registry gives the study phase as NA and lists healthy participants.

Participants were assigned to watch either an epigenetics video or a nanotechnology video. The registry lists no masking. The two arms therefore represent different video content, with the nanotechnology video serving as the comparator. Each video is described as brief, at <5 minute. The registry record does not report how random assignment was generated, whether allocation was concealed, or whether the video conditions were otherwise matched.

The listed enrollment is 2040. The primary endpoint is knowledge and understanding of epigenetics information, assessed after the intervention video. The record gives arm-level outcome counts of 1310 for the epigenetics video and 313 for the nanotechnology video. The primary analysis population excluded inattentive responders, defined by an incorrect response to an attention-check question or self-reported paying no or a little bit of attention. The record does not explain the difference between the listed enrollment and the counts in the primary outcome results.

The study began on 2025-06-12, reached primary completion on 2025-07-18, and has a completed status. Acceptability of epigenetics information and perceptions of epigenetic information are listed as secondary outcomes, but their results are not reported in the registry record. The trial’s original design assumptions and its detailed statistical analysis plan are also not reported in the registry record.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Analysis population for the primary outcome, as defined in the registry: We excluded participants who met the following criteria: inattentive responders (defined as answering incorrectly to an attention check question \[to show you read carefully, leave this question blank\] OR participants who self-reported paying no or a little bit of attention to the survey questions), completing the survey in less than half of the median response time, and not watching the full experimental or control condition video. This resulted in n=1623 participants in the analytical sample.

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 Knowledge & Understanding of Epigenetics Information, measured over After intervention video.

The primary endpoint is titled Knowledge & Understanding of Epigenetics Information. It is a continuous sum score: the number of correct answers across 8 individual knowledge items. The score ranges from 0 points to 8 points, and higher scores indicate greater epigenetics knowledge according to the registry description. The outcome was measured after the intervention video.

A sum score makes the responses to the individual knowledge items interpretable as an overall measure of correct answers, rather than treating each item as a separate primary endpoint. Comparing the mean scores describes the average level of knowledge measured by this scale in each group. As a general statistical point, a mean is a useful summary for a continuous score when the question concerns the groups’ average responses; it does not describe every participant’s score or the distribution of answers to each item.

The record also defines an analysis population by excluding inattentive responders. This affects who contributes to the posted endpoint result and should be kept in mind when interpreting the group means. The registry gives no item-level results, evidence about the scale’s measurement properties, or baseline knowledge scores. Those details are not reported in the registry record.

7. Results Posted in the Registry

• Nanotechnology Video: mean 4.09 versus 5.44 on control; difference -1.35 (95% CI -1.65 to -1.05), standardized effect d = -0.56; z-test p = <0.001.

8. Statistical Interpretation

9. Statistical Methods Explained

What does the mean difference represent?

The endpoint is a continuous sum score, and the registry reports a mean for each arm. A mean difference compares those group averages. The registry’s own reported estimate is 1.35 for the comparison of final values, with the epigenetics-video group having the higher mean. The recalculation is written as nanotechnology video minus epigenetics video, so its estimate is -1.35. The sign depends on which group is subtracted from which; the size and direction of the underlying contrast are the same when the ordering is made explicit.

As a general statistical explanation, a mean difference retains the score’s original units. Here, those units are points on a sum score from 0 points to 8 points. This makes the estimate interpretable as a difference in average score points. It does not imply that every participant in one group scored above every participant in the other, nor does it describe the spread of individual scores by itself.

What does the t-test assess?

The registry reports a 2 sided t-test for the mean difference in final values. As a general explanation, a t-test evaluates whether the observed difference in group means is compatible with a null model in which the population means are equal, accounting for variability and sample size under its assumptions. A 2 sided test considers departures in either direction. The posted p-value is <0.001. A p-value is a measure of how unusual data at least as inconsistent with the null model would be if that model and the test assumptions held; it is not the probability that the null hypothesis is true and it does not measure the size or practical importance of a difference.

The registry labels the analysis as superiority. That label describes the form of the statistical comparison; it does not by itself establish that the difference is important for communication practice or clinical use. The study’s primary outcome is a knowledge score, and no threshold for a meaningful difference is reported in the registry record.

How should the confidence interval be read?

The registry reports a 95% confidence interval from 1.06 to 1.65 for its mean difference. In general, a confidence interval is constructed by a procedure that, under the model and repeated use of the same procedure, would cover the target parameter at the stated rate. For an individual study, the interval shows the precision of the estimate across values compatible with the observed data and assumptions. It is not a statement that 95% of individual participants’ scores fall within those endpoints.

The recalculation gives a 95% interval from -1.654 to -1.046 because it uses the reverse contrast. Both intervals exclude zero. The results have the same direction when the subtraction order is accounted for. Since the registry’s own analysis is reported, it is useful to retain that result as the sponsor’s primary estimate and use the recalculation as a check based on the posted summaries.

What does the recalculation use?

The recalculated contrast uses the posted arm-level means and summary variability, with a pooled standard deviation of 2.417. The standardized effect size is -0.559 under the nanotechnology-minus-epigenetics ordering. As a general explanation, a standardized effect expresses a mean difference relative to a measure of variability, making it unitless; its sign still depends on the group ordering. It does not replace the difference in score points and should not be read as a direct measure of clinical or communication importance.

The registry reports no discrepancy between its result and the recalculation. The recalculated estimate and interval are unadjusted calculations from posted summary statistics, while the registry’s t-test result is the sponsor’s reported analysis. The posted results do not give further detail on the t-test implementation or the exact analysis plan.

Why can variability matter?

As a general statistical point, variability describes how dispersed observations are around a group average. Greater variability makes a given difference in means harder to estimate precisely, while larger analyzed groups generally improve precision when other assumptions are comparable. In this study, arm-level confidence intervals are reported for the means, and a pooled standard deviation is available for the recalculation. The registry does not provide score distributions or diagnostic checks, so the shape of the score distributions and the adequacy of model assumptions cannot be assessed from the posted record.

For continuous outcomes, unusual skew, clustering, or unequal variability can affect the performance of common mean-comparison methods. These are general considerations, not reported problems in this study. The registry does not report tests or adjustments addressing them. No additional analytic features should be inferred from the posted t-test label.

What is not documented?

The registry record does not report the original sample-size justification, the planned analysis population beyond the attention exclusions stated for the outcome, missing-data procedures, interim analyses, or a detailed protocol for handling multiple outcomes. It lists two secondary outcomes and describes a total of three outcome measures, but secondary results are not reported in the registry record. These omissions limit a complete assessment of the analysis strategy and the extent to which the posted result follows a prespecified plan.

10. Confidence Intervals and Precision

The registry’s own estimate of the mean difference is 1.35, with a 95% confidence interval from 1.06 to 1.65. The interval is above zero, and the reported p-value is <0.001. In context, the point estimate is expressed in score points on a scale that ranges from 0 points to 8 points. The interval communicates uncertainty in the estimated difference between group means, not variation among individual participants.

The recalculation uses the reverse group ordering and reports a mean difference of -1.35, with a 95% confidence interval from -1.654 to -1.046. Its endpoints are likewise on one side of zero. The opposite signs arise because this calculation subtracts the epigenetics-video mean from the nanotechnology-video mean, whereas the registry’s positive result is oriented in the other direction. The interval limits differ in their displayed precision and values because the registry reports its own analysis while the recalculation uses posted summary statistics. The registry record does not report a discrepancy.

As a general explanation, narrower confidence intervals indicate greater precision for the estimated parameter, while wider intervals indicate more uncertainty. Precision depends on factors such as variability and analyzed sample size, as well as the statistical model. The endpoint confidence intervals for each arm are 5.31 to 5.57 for the epigenetics video and 3.81 to 4.36 for the nanotechnology video. Those intervals summarize uncertainty around the arm means; they are not individual score ranges.

The interval should not be treated as a guarantee that the true difference lies within its endpoints, nor does it resolve limitations in the analysis population or missing-data reporting. A confidence interval also does not answer whether a difference is practically important. The registry does not report a threshold for meaningful change in knowledge score.

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 sample-size figures are planning illustrations based on the observed effect, not the trial’s own design justification. For this continuous outcome, the figures are participants per arm, rather than total events. They use the stated assumptions of a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. Each planning row uses the stated fraction of the observed effect: 100%, 75%, or 50%.

The 80% power column gives the illustrative participants per arm for a design with an 80% chance of detecting the specified effect under those assumptions, if that effect and the model assumptions were correct. The 90% power column gives the corresponding per-arm planning figure for a 90% chance. These are prospective planning concepts: power is the probability of detecting a specified effect under a specified design and statistical model, not a measure of what the completed study achieved.

The listed figures are 51 participants per arm for 80% power and 68 for 90% power when planning for 100% of the observed effect. For 75% of the observed effect, the figures are 90 and 120 participants per arm. For 50% of the observed effect, they are 202 and 270 participants per arm. Smaller effects need more participants to detect under otherwise comparable assumptions, and the higher power target also requires more participants in each listed row.

This is not observed power. The figures do not recreate the original enrollment plan, which is not reported in the registry record. They are illustrative calculations anchored to the observed estimate and stated assumptions, not evidence that the study was designed around these values.

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 = -1.350; pooled standard deviation σ = 2.417.
2. n = 2 × (1.96 + 0.842)² × 2.417² / -1.350² = 50.3, rounded up to 51 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 <- -1.35                      # observed difference in means
sigma <- 2.41659185939221                     # 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(7020234)
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 = 51 (80% power), 68 (90% power)
 75% of observed effect: n per arm = 90 (80% power), 120 (90% power)
 50% of observed effect: n per arm = 202 (80% power), 270 (90% power)
power.t.test: 51.3 
Simulated power at n = 51 per arm: 0.797 (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. Analyses Reported by the Sponsor

The registry’s own analysis reports a positive mean difference of 1.35 for final values, with a 95% confidence interval from 1.06 to 1.65 and p < 0.001. The reported analysis is a 2 sided t-test and identifies the comparison as superiority. The arm means are 5.44 for the epigenetics video and 4.09 for the nanotechnology video.

The unadjusted recalculation writes the contrast in the reverse order, nanotechnology video minus epigenetics video. It therefore gives -1.35, with a 95% confidence interval from -1.654 to -1.046 and p < 0.001. The negative sign does not indicate a disagreement: it reflects the reversed subtraction order. The posted record marks no discrepancy, and the registry’s own analysis remains the main reported result.

The two confidence intervals have different displayed limits and precision. The sponsor’s result is the registry analysis; the recalculated result comes from posted summary statistics and is an unadjusted check. They should not be treated as identical calculations or as independent studies. There is no indication in the registry record that the sponsor’s result should be replaced by the recalculation.

14. Multiplicity, Missing Data and Analysis Populations

The registry lists one primary outcome, Knowledge & Understanding of Epigenetics Information, and two secondary outcomes: Acceptability of Epigenetics Information and Perceptions of Epigenetic Information. It also gives a count of three outcome measures and two reported analyses. Results for the secondary outcomes are not reported in the registry record. The record does not describe a multiplicity adjustment, a hierarchy among secondary outcomes, or how interpretation was planned across outcomes. The statistical plan for controlling or addressing multiple comparisons is therefore not reported in the registry record.

As a general statistical point, when several outcomes or comparisons are examined, the chance of at least one apparently notable result can increase if each is interpreted without regard to the others. Prespecifying a primary endpoint and a strategy for multiple testing can help distinguish the main confirmatory question from additional analyses. The registry identifies a primary outcome, but does not report enough detail to determine how multiplicity was handled across all measures or analyses.

The primary outcome description specifies exclusions for inattentive responders: an incorrect answer to an attention-check question or self-report of paying no or a little bit of attention. The outcome arm counts are 1310 and 313, while enrollment is 2040. The registry does not report the number excluded for each reason, the number with missing endpoint data, or how missing data were handled. It also does not state whether participants were analyzed according to assigned group in an intention-to-treat analysis or whether any other analysis population was used.

These reporting gaps matter because the analyzed set can differ from the randomized or enrolled set, and missingness or exclusions can affect how representative the analyzed results are. The available information identifies the stated attention exclusions and outcome counts, but does not allow the full flow from enrollment to analysis to be reconstructed. No further assumptions about exclusions, missingness, or the analysis population are warranted from the registry record.

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

The posted primary result describes a difference in average knowledge scores after two videos. Participants in the epigenetics-video group had a mean score of 5.44, compared with 4.09 in the nanotechnology-video group. The registry’s reported mean difference is 1.35, with a 95% confidence interval from 1.06 to 1.65 and p < 0.001. The scale counts correct responses across 8 items, ranges from 0 points to 8 points, and assigns higher scores to higher epigenetics knowledge.

This result does not show that every participant learned more, because group means do not describe the full distribution of individual scores. It also does not show how much participants knew before viewing the videos: a baseline knowledge score is not reported in the registry record. The measured endpoint was taken after the intervention video, so the posted comparison concerns post-video scores rather than reported within-person change.

The finding addresses knowledge and understanding as measured by the registry’s sum score. It does not establish later retention, behavior change, acceptance of epigenetics in clinical settings, clinical decision-making, or health outcomes. Although acceptability and perceptions are listed as secondary outcomes, their results are not reported in the registry record.

The comparison was between an epigenetics video and a nanotechnology video, not between a video and no information. The outcome therefore should be understood in the context of these two communication conditions. The registry does not report enough detail about video content or matching to attribute the score difference to any particular feature of the videos.

Finally, the result pertains to the analyzed participants after the described attention exclusions. The relation between listed enrollment and analyzed counts, the handling of missing data, and generalizability beyond this survey population are not fully described. Statistical evidence for a difference in the posted score is not by itself a judgment about the practical importance of that difference.

16. Why This Trial Matters Statistically

This study illustrates how a communication experiment can turn a broad question about public understanding into a measurable endpoint. The primary outcome is a sum of correct answers about epigenetics, and the randomized comparison asks whether the mean score differs after an epigenetics video versus a nanotechnology video. This makes the statistical target concrete: a difference in average post-video knowledge scores on a stated scale.

The report also illustrates why direction and scale matter when reading a contrast. The sponsor reports a positive mean difference of 1.35, while the recalculation reports -1.35 because it subtracts the groups in the opposite order. Naming the comparison order makes the signs interpretable and avoids mistaking equivalent contrasts for conflicting findings.

Precision is important alongside the point estimate. The registry’s 95% confidence interval, from 1.06 to 1.65, indicates a relatively bounded range of estimates under the analysis, while still leaving uncertainty about the population difference. The interval and p-value describe statistical evidence; they do not establish practical importance, persistence of knowledge, or changes in acceptability and perceptions.

The record also demonstrates the value of reporting analysis populations and outcome flow. It states that inattentive responders were excluded, but does not report their number or the missing-data approach. Enrollment and primary outcome counts differ, and the registry does not explain that difference. Without this information, readers cannot fully judge how the analyzed group was formed.

Finally, the planning illustrations show the general relationship between effect size, power, and sample size, but do not reveal the trial’s original design rationale. Distinguishing planning calculations from the completed study’s observed results is essential for sound interpretation.

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 registry record gives limited detail about participant characteristics beyond describing the population as healthy and the study as a national survey. It does not report demographic composition, recruitment methods, survey setting, or the degree to which participants represent the broader public. This limits assessment of how well the result may generalize beyond the analyzed participants.

The intervention descriptions are brief: participants watched an epigenetics video or a nanotechnology video, each described as <5 minute. The registry does not report the video scripts, specific content, presentation conditions, or whether length and format were matched. Because the comparator is another video rather than a no-video condition, the observed contrast is specific to the two video conditions and cannot isolate the effect of receiving information from the effect of video exposure generally.

The primary outcome is a sum score of correct answers across 8 items. Item wording, item-level responses, validation details, and evidence about reliability are not reported in the registry record. A total score provides an overall measure as defined by the study, but the available description does not show which knowledge areas account for the group means or how well the score captures broader understanding.

Primary outcome counts are 1310 and 313, compared with listed enrollment of 2040. The registry describes attention-related exclusions but does not give counts by reason or explain the full participant flow. It also does not report missing-data handling, baseline knowledge, or whether any analyses adjusted for other variables. These omissions limit evaluation of selection and analysis choices.

The original sample-size justification, detailed protocol, interim analyses, and full multiplicity strategy are not reported in the registry record. Secondary outcomes are listed but their results are not reported. These limitations constrain interpretation beyond the posted primary score comparison.

18. Related Tutorials

19. Related Statistical Calculators

20. Sources

• ClinicalTrials.gov: National Survey to Understand Ethical, Legal and Social Issues in Communicating to the Public About Epigenetics — NCT07020234.
• Registry record last updated 2026-10-14; status last verified 2026-10.
• Results first posted 2026-10-14.
• 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

NCT07020234 is a completed randomized, parallel-group behavioral survey study sponsored by Washington University School of Medicine. Healthy participants were assigned to an epigenetics video or a nanotechnology video. Listed enrollment is 2040; the primary outcome results report 1310 participants in the epigenetics-video group and 313 in the nanotechnology-video group.

The primary outcome was a post-video sum score of correct answers across 8 epigenetics knowledge items, ranging from 0 points to 8 points. The arm means were 5.44 and 4.09. The registry reports a mean difference of 1.35, a 95% confidence interval from 1.06 to 1.65, and p < 0.001. The analysis excluded participants meeting the stated attention-related criteria.

Acceptability and perceptions are listed as secondary outcomes, but their results are not reported in the registry record. Missing-data handling, detailed analysis plans, and the original sample-size justification are also not reported.