Organizational Skills Training - Tier 2 (OST-T2): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Organizational Skills Training - Tier 2 (OST-T2) (NCT03443323), a randomized na study. The primary outcome is Students' Organizational Functioning - Teacher Report.

2. Clinical Question

3. Trial Design

The registry describes a randomized, parallel-group, cluster-randomized evaluation of OST-T2. Participating schools, rather than individual students, were randomly assigned to OST-T2 or treatment as usual. The record reports 22 participating schools in Pennsylvania and New Jersey and enrollment of 186. Students were in grades 3 through 5; the participating schools included urban and suburban settings and served a diverse population. The record gives the study status as completed.

In the intervention group, school staff delivered small-group training in organizational skills. The program focused on organization, time management, and planning, with parent and teacher involvement intended to support students’ use of skills. School staff received training and consultation from intervention experts. The treatment-as-usual group continued strategies already used by schools to address these skill-related difficulties. The record does not specify the exact strategies used at each school.

The masking field is listed as single. Which people were masked, and what information they were masked to, is not reported in the registry record. The record identifies the primary outcome as teacher-reported organizational functioning and gives assessment times as baseline, 14-weeks (post-treatment), 5-months and 12-months. The reported primary analysis is a mixed models analysis, but details of the model are not included in the posted results.

Phase is listed as NA. The registry lists secondary outcomes concerning homework performance reported by teachers and parents, academic proficiency, academic competence, academic grades, and student self-efficacy. It identifies 8 outcome measures and 8 analyses. The particular analysis populations, allocation counts by arm, and the distribution of participants across schools are not reported in the registry record. Those omissions limit how fully the design and the analysis can be reconstructed from the record alone.

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: Data from 186 student participants were evaluated for this study. Data were derived from parents, teachers, and child self-report. One participant of the 186 was withdrawn prior to the intervention period because this student was found not to meet study eligibility criteria.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Note that 180 participants provided data that were analyzed. Data were missing for 5 participants on this measure.

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.

Population: The PIs withdrew one participant before the study intervention period because this person was found not to meet study eligibility criteria.

6. Primary Endpoint

The registry lists the primary outcome as Students' Organizational Functioning - Teacher Report, measured over Baseline, 14-weeks (post-treatment), 5-months and 12-months.

The primary endpoint was students’ organizational functioning based on teacher report using the Children’s Organizational Skills Scales - Teacher Version (COSS-T). The registry describes the COSS as assessing organization, time management, and planning functioning at home and school over several assessment times. The primary endpoint used the total score across 28 items rather than the three COSS subscales, with the mean item score used in analyses. The possible range is from 1 to 4, with higher scores indicating a worse outcome.

The registry states that the scale uses a 4-point rating scale, from “Hardly ever or never” to “Just about all of the time,” and describes the total score as having good discriminant validity and sensitivity to treatment effects. A teacher report is one way of measuring students’ functioning in contexts where organizational demands arise. The stated assessment schedule includes baseline, 14-weeks (post-treatment), 5-months and 12-months, allowing assessment across more than one follow-up time.

The endpoint is a continuous score, so the mean is a relevant summary of its central level. However, the posted primary result does not give the arm-specific means, the modeled contrast, or its confidence interval. The endpoint definition and scoring direction therefore clarify what the measure represents, but the p-value alone does not quantify the size or precision of the difference between groups.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the primary endpoint as a continuous measure and reports a mixed models analysis. A continuous outcome can be summarized using means, and a model can compare groups while accounting for the structure of repeated measurements or clustered observations, depending on the model specification. The registry does not describe the precise model, so these are general explanations of the method category rather than claims about the exact analysis used in this trial.

What does a mixed models analysis do?

In general, mixed models can represent both systematic group or time patterns and variation among related observations. They are often used when observations are repeated for the same participant or when participants are grouped within settings such as schools. For a cluster-randomized trial, accounting for the school-level assignment and the relationships among students within schools is important for valid uncertainty estimates. The registry reports a mixed models analysis, but does not specify the model terms, covariance structure, estimation method, or how the school clusters were represented. Those details are not reported in the registry record.

The primary outcome was measured at baseline, 14-weeks (post-treatment), 5-months and 12-months. Repeated measurements can carry information about change over time, but the posted result does not identify the particular time contrast or overall test associated with p < 0.001. It is therefore not possible to say from this record whether that p-value refers to a single follow-up, a comparison across time points, or another model contrast. The exact estimand—the quantity the analysis was designed to estimate—is not reported in the registry record.

What does the p-value say?

In general, a p-value describes how compatible the observed data are with a specified null hypothesis, under the assumptions of the analysis. The reported p < 0.001 is the sponsor’s result for the primary superiority analysis. It is not an estimate of the treatment difference, a probability that the null hypothesis is true, or a measure of clinical importance. Without the contrast estimate and its uncertainty interval, the result cannot show how large or precisely estimated the difference was. The registry does not provide those quantities for the primary analysis.

A confidence interval gives a range of values compatible with the data and the analysis assumptions, and helps show the precision of an estimate. The endpoint description identifies 95% Confidence Interval as the dispersion measure, but the reported primary analysis has no estimate or interval values. Thus, there is no posted primary confidence interval to interpret. A small p-value and a narrow confidence interval answer different questions: the former concerns compatibility with a null hypothesis, while the latter communicates estimation uncertainty.

Why does cluster assignment affect analysis?

In general, observations from people in one school may be more alike than observations from different schools. If analysis treats all students as fully independent, it can understate uncertainty when within-school similarity is present. Cluster-aware methods account for the assignment unit and the correlation structure. The record explicitly notes that a simple individual-level recalculation would be misleading and reports only the sponsor’s own analysis. It does not report a cluster-level correlation estimate, school-level sample sizes, or enough model details to reproduce the analysis.

Mixed models may be appropriate for complex data structures, but the name of a method alone does not reveal whether every relevant design feature was handled as intended. Readers would need details about model terms, assumptions, and the way missing observations and repeated measures were treated. These are not reported in the registry record. The posted p-value should therefore be attributed to the sponsor’s model, with the limits on independent assessment kept in view.

What do planning calculations mean?

General sample-size illustrations translate an assumed effect and design choices into a planning quantity. The stated assumptions for the illustrations include a two-sided significance level of 0.05, equal allocation between arms, a normal approximation, and effects defined as stated fractions of the observed effect. For non-time-to-event outcomes, the stated quantity is participants per arm for a specified power; time-to-event illustrations instead concern total events. Such illustrations are planning exercises, not observed power and not evidence that the trial was designed around those assumptions.

The registry does not report the trial’s own sample-size justification, the effect size used in its planning, or whether the planning illustrations reflect the original protocol. In a cluster-randomized study, planning also depends on features of the clustering and analysis. Those details are not reported in the registry record. A planning illustration should therefore not be treated as a description of the study’s original design or as a substitute for the observed effect estimate and its confidence interval.

The record gives a superiority analysis, but does not report the hypotheses in more detail, the model’s degrees-of-freedom method, or whether any interim analyses were conducted. These aspects of the statistical plan are not reported in the registry record. General explanations of mixed models and p-values can help frame the reported result, but cannot fill in those missing analysis details.

10. Analyses Reported by the Sponsor

The registry reports the sponsor’s own mixed models analysis of the primary outcome, with p < 0.001. The record explicitly notes that the trial was cluster-randomized and that a simple individual-level recalculation would be misleading; accordingly, only the sponsor’s own analysis is shown. There is no recalculated primary estimate or p-value to compare with the sponsor’s result.

The sponsor’s reported analysis therefore takes the central role in interpreting the posted primary result. However, its estimate, confidence interval, arm-specific means, model specification, and exact time contrast are not reported in the registry record. The result can be described as the sponsor’s reported statistical test, but its magnitude, direction, and precision cannot be independently evaluated from the reported statistics.

No discrepancy between a recalculated result and the sponsor’s analysis is presented. This is not a case where two estimates can be compared to investigate why they differ: the registry’s cluster-design note is the reason a simple individual-level recalculation is not used. The interpretation should remain limited to the sponsor’s reported p-value and the available endpoint and design information.

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 8 outcome measures and 8 analyses. Alongside the primary teacher-reported organizational functioning measure, it lists secondary outcomes concerning homework performance by teacher and parent report, academic proficiency, academic competence, academic grades, and student self-efficacy. Reporting multiple outcomes can raise a multiplicity question: when many hypotheses are tested, the chance of at least one apparently unusual result can increase. This is a general statistical concern, not evidence that the reported findings are false.

The registry record does not state whether the analyses were organized in a hierarchy, whether any adjustment for multiple testing was used, or whether all outcomes and analyses were prespecified. These details are not reported in the registry record. The primary p-value should therefore be interpreted as the reported test result, without assuming that it was or was not adjusted for multiplicity. The record does not provide enough information to reconstruct the family of tests or evaluate the implications of any adjustment.

For the primary endpoint, the registry states that 180 participants provided data analyzed and that data were missing for 5 participants on this measure. The handling of those missing data is not reported in the registry record. It does not state whether the mixed model used all available measurements, whether any imputation was performed, or how missingness assumptions were assessed. The record also does not describe the analysis population beyond the statement about participants with data analyzed for the measure.

Enrollment is reported as 186, but the record does not give a complete accounting of participants by arm, school, follow-up time, or analysis population. It is therefore not possible to reconcile enrollment with the primary measure’s analyzed and missing-data counts from the information reported. The handling of participants who may have missed particular assessments, and whether all randomized schools or students were retained in the analysis, are not reported in the registry record. These gaps matter for judging the scope of the result, but they do not change what the posted p-value itself states.

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 no serious adverse events in either group. The OST-T2 group lists 97 participants at risk for serious adverse events and 0 affected; the treatment-as-usual group lists 88 at risk and 0 affected. The same group counts are reported for other adverse events, with 0 affected in each group. Deaths are reported as 0 in both groups. No serious adverse event terms are listed.

These figures describe the events recorded in the registry for the stated groups and at-risk counts. They do not show whether every possible event was collected in the same way, how long each participant was observed for safety, or whether particular event definitions or reporting thresholds were applied. Such details are not reported in the registry record. Zero recorded events should not be interpreted as proof that no adverse events could occur; it means no events are listed for these categories in the posted results.

The listed at-risk counts differ between groups, but the registry does not explain the relationship between those counts and overall enrollment or the primary outcome analysis population. The safety figures should be read separately from the primary organizational-functioning result. They do not provide information about the size or direction of the primary endpoint contrast.

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

The posted primary result establishes that the sponsor reported a mixed models superiority analysis for teacher-reported organizational functioning with p < 0.001. It does not establish the size of the estimated difference, its direction, or its precision. The registry does not report a primary contrast estimate, group means, or confidence interval. Those omissions prevent a fuller assessment of the practical scale of the observed result.

Higher COSS-T scores indicate a worse outcome. Because the record does not report which group had the higher score or the modeled contrast’s sign, the primary p-value alone cannot show whether the difference favored one group on the scale. It also does not tell readers whether any difference was meaningful in the settings and contexts represented by the measure. The outcome definition explains what the scores mean, but the reported test does not supply the missing comparison details.

The result is specific to the reported teacher measure and the analysis used. The registry lists several other outcome areas, but the primary p-value does not summarize homework performance, academic measures, or self-efficacy. Nor does it provide separate evidence at baseline, 14-weeks (post-treatment), 5-months and 12-months. The exact time contrast associated with the reported test is not reported in the registry record.

The trial is cluster-randomized by school, and the registry says that a simple individual-level recalculation would be misleading. Interpretation should therefore rely on the sponsor’s reported mixed models analysis, while recognizing that its details are not available in the registry record. The result does not provide a basis for reconstructing the analysis or for claiming that the same p-value would arise from an alternative model.

Finally, a p-value is not a probability that the intervention is beneficial, nor is it a measure of outcome importance. The posted data support describing the sponsor’s statistical finding and the outcome’s scoring rules. They do not, by themselves, establish the magnitude, durability, or broader applicability of any group difference. Those questions require information beyond the primary statistic reported in the registry.

14. Why This Trial Matters Statistically

This trial illustrates why the unit of randomization matters when interpreting clinical research. Schools were assigned to study groups, and students were nested within those settings. In general, outcomes from participants in the same cluster may be related, so an analysis that ignores the school-level design can give misleading uncertainty. The registry explicitly recognizes this concern and presents the sponsor’s mixed models analysis rather than a simple individual-level recalculation.

It also illustrates the difference between evidence from a statistical test and an estimate of an effect. The reported p-value is small, but the registry does not provide the primary contrast, its confidence interval, or group-specific means. Without those quantities, readers cannot assess the estimated magnitude or precision. Reporting an estimate with an interval alongside a test result would allow a more complete statistical interpretation.

The outcome itself highlights the importance of understanding measurement direction and scope. The COSS-T total score is a mean item score, and higher scores indicate worse organizational functioning. Knowing the direction is necessary to interpret a contrast, but the registry does not report that contrast’s direction. The measure also reflects teacher report; its result should not be treated as interchangeable with parent report, academic performance, or student self-efficacy.

Finally, the record makes visible several common limits of registry results: incomplete model details, limited reporting of missing-data handling, and no stated approach to multiplicity across listed outcomes. These omissions do not erase the reported result. They define how far readers can go in evaluating it and why statistical interpretation should distinguish the reported test from the broader evidence needed to understand size, precision, and robustness.

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.

The primary limitation for interpretation is that the registry reports p < 0.001 without the modeled group difference, its confidence interval, or arm-specific summaries. Although the endpoint description identifies 95% Confidence Interval as the dispersion measure, no interval values are reported for the primary analysis. The direction and magnitude of the contrast therefore cannot be determined from the posted statistic.

The record describes the analysis as mixed models but does not provide the model specification. It does not state how the school clusters were represented, which time effects or interactions were included, what covariance structure was used, or which contrast produced the reported p-value. The registry notes that an individual-level recalculation would be misleading, so there is no independent recalculation to assess alongside the sponsor’s analysis.

Missing-data information is limited. The record states that 180 participants provided data analyzed and that data were missing for 5 participants on the primary measure, but does not report how missing observations were handled or what assumptions were made. It also does not provide a detailed analysis population or a complete participant accounting by group, school, and time point.

There are 8 listed outcome measures and 8 analyses, but the registry does not report whether multiplicity was addressed or whether the outcome and analysis choices were prespecified. Masking is labeled single, but the masked parties are not identified. The detailed statistical plan, interim-analysis information, and sample-size justification are not reported in the registry record.

The primary measure is teacher-reported and covers organizational functioning as assessed by the COSS-T. The record lists other outcome areas, but the primary result cannot stand in for results on those measures. The exact connection between the reported p-value and the stated assessment times is also not described. These limitations are specific to what the registry record reports and leave important questions about effect size, timing, and analysis conduct unresolved.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Organizational Skills Training - Tier 2 (OST-T2) — NCT03443323.
• Registry record last updated 2024-12-16; status last verified 2024-10.
• Results first posted 2024-12-16.
• 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

NCT03443323 is a completed, randomized, parallel-group, cluster-randomized evaluation of Organizational Skills Training - Tier 2 (OST-T2) against treatment as usual. The registry reports enrollment of 186 students in grades 3 through 5 from 22 schools in Pennsylvania and New Jersey. OST-T2 involved small-group skills training with parent and teacher involvement; comparison schools used strategies already in place.

The primary outcome was teacher-reported organizational functioning measured with the COSS-T. The sponsor’s mixed models superiority analysis is reported as p < 0.001. The registry does not report the group contrast, confidence interval, or model details. It notes that a simple individual-level recalculation would be misleading because of the cluster-randomized design. The record also lists secondary academic and homework outcomes, and reports no serious or other adverse events and no deaths in either group.