Accelerating Word Learning in Children With Language Impairment: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Accelerating Word Learning in Children With Language Impairment (NCT01829360), a randomized na study. The primary outcome is Change in Words Known From Pre- to Post-treatment.

2. Clinical Question

The study asked how to arrange repeated exposure to new words during interactive book reading for Kindergarten children with Specific Language Impairment (SLI). The investigators described a target of 36 exposures and compared approaches that varied how many times words were repeated within a book and how often the book was read. Their stated hypothesis was that reading books many times would be more effective than repeating words many times within a book. That is the study’s hypothesis, not a result.

The primary measure counted words a child could define with at least partial accuracy. The registry record does not report a single numerical comparison answering the question, so the stated hypothesis cannot be judged from a one-number treatment contrast in the registry record.

3. Trial Design

The registry record describes a randomized, single-masked crossover study with 35 participants and a behavioral interactive book-reading intervention. In a crossover design, participants receive more than one treatment condition in a planned sequence, so treatment comparisons may be informed by outcomes under different conditions in the same participant. The record lists four sequences rather than a simple pair of parallel groups.

Two sequences began with the standard treatment, dose 6 x dose frequency 6, and then moved to an alternative: either high dose, dose 9 x dose frequency 4, or high dose frequency, dose 4 x dose frequency 9. The other two sequences began with one of those alternatives and then received the standard treatment. Thus, sequence and treatment period are relevant when interpreting a crossover comparison. Details of any washout period, carryover precautions, or analysis accounting for period and sequence are not reported in the registry record.

The intervention is described as interactive book reading, with dialogic reading and shared book reading also named. Each of the two treatments taught 30 new words. Treatment lasted 10 to 23 sessions, approximately 5 to 12 weeks. The design aimed to compare different arrangements of word dose and reading frequency while considering the stated target of 36 exposures. The registry record does not provide enough information to infer how exposure opportunities were delivered beyond the arm descriptions.

Single masking is recorded, but the registry record does not identify who was masked or how masking was maintained. The study is marked completed, and its phase is recorded as NA. The registry record does not report further details about randomization procedures, sequence allocation, adherence, or whether participants completed both treatment periods.

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

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 Words Known From Pre- to Post-treatment, measured over Pre- and Post-treatment with treatment lasting 10 to 23 sessions (approximately 5 to 12 weeks).

The primary endpoint is change in words known from pre- to post-treatment, measured as the number of words learned. In each treatment, children were taught 30 new words and assessed on whether they could define each one. A definition received a score from 0 to 3, with the scoring criteria distinguishing absent or incorrect definitions, vague definitions or appropriate use in a sentence, partially accurate definitions, and complete and accurate definitions. For the primary analysis, scores of 2 or 3 counted as knowing the word; scores of 0 or 1 counted as not knowing it. The resulting score could range from 0 to 30 words known, with higher scores indicating a better outcome.

This endpoint translates performance on the taught vocabulary into a count that can be compared before and after treatment. It focuses on whether children demonstrated at least partial knowledge of the word’s meaning, rather than requiring a fully complete definition for a word to count as known. The registry record reports the outcome as a mean with standard error, a way to describe the average score and its sampling uncertainty. The timeframe is pre- and post-treatment, with treatment lasting 10 to 23 sessions, approximately 5 to 12 weeks.

The record identifies more than one category or time point for the primary outcome, and it is not reduced to one comparison. A numerical primary-outcome estimate for a single treatment contrast is not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record describes a continuous primary outcome summarized as a mean with standard error. The score is a count of words known, defined by the study’s scoring rule. A mean describes the average score across observations included in a particular analysis. A standard error describes the uncertainty in estimating that mean from the observed data; it is not the spread of individual children’s scores. The registry record does not report a single mean contrast or its standard error for one primary comparison.

What does a crossover design compare?

In a crossover study, the same participant may receive more than one condition in sequence. This can allow comparisons that account for stable differences between participants, because each participant contributes observations under multiple conditions. However, outcomes can also depend on treatment period, sequence, or effects of an earlier condition that persist into a later one. These are general considerations for crossover designs, not claims about what happened in this study. The record lists four treatment sequences but does not report whether the analysis adjusted for period, sequence, or carryover, or whether a washout was used.

What do mean and standard error communicate?

A mean gives a central summary of the words-known score. The standard error indicates how precisely that mean is estimated. A confidence interval combines an estimate with an uncertainty range and is often more informative than a p-value alone because it shows both the plausible size and direction of an effect under the model. General statistical interpretation depends on the analysis model and its assumptions. No single primary estimate, confidence interval, or p-value is reported in the registry record, so the magnitude and precision of a treatment contrast cannot be evaluated.

Why does the outcome definition matter?

The endpoint does not count every definition score as a distinct level in the final words-known measure. Scores of 2 or 3 count as a known word, while scores of 0 or 1 count as not known. This threshold creates a count of words meeting the study’s criterion. It is useful to keep that definition in mind: a partially accurate definition counts in the same way as a complete and accurate definition for this analysis, while a correct use in a sentence or a vague definition does not count as knowing the word under the stated rule. The registry record describes the score range as 0 to 30.

How should planning calculations be read?

The registry record describes sample-size planning illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The effect to detect is described as a stated fraction of the observed effect. These calculations are planning illustrations, not observed power and not evidence that the study had a particular probability of detecting an effect. Their interpretation depends on the effect and other assumptions used in the calculations. Numerical planning values and the fractions used are not reported in the registry record, so no specific participant count can be stated.

For continuous outcomes, planning illustrations expressed as participants per arm are different from the actual enrollment and from the number analyzed. The record reports 35 enrolled participants, but does not report how many contributed to a given analysis. An illustration under equal allocation between two arms also does not by itself describe the allocation or analysis of this four-sequence crossover design. It should not be treated as a reconstruction of the study’s original design justification; that justification is not reported in the registry record.

What analysis details are not available?

The registry record does not report the statistical model, the unit of analysis, the treatment contrast definition, or the method used to account for repeated measurements. It also does not report whether standard errors were model-based or calculated by another approach. These details matter because the same outcome data can yield different estimates and uncertainty measures under different valid models, especially when observations are repeated within participants. The methods cannot be inferred from the endpoint label or from the fact that the trial was randomized and crossover.

The record lists 3 outcome measures and 3 analyses, while the primary outcome has several categories or time points and is not reduced to one comparison. Those counts do not reveal which specific contrasts were estimated or how they were modeled. The record also names secondary outcomes, Interim Definition and Interim Naming, but does not specify their analysis methods. No additional assumptions about the statistical plan, interim monitoring, or multiplicity adjustment can be made from these descriptions.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists 3 outcome measures and 3 analyses. It also identifies the secondary outcomes Interim Definition and Interim Naming, and notes that the primary outcome has several categories or time points rather than one reduced comparison. These features mean that more than one outcome summary or contrast may be relevant. When many hypotheses are tested, the chance of at least one apparently notable result can increase; this is a general statistical concern, not a conclusion about this study’s analyses.

Whether the investigators prespecified a primary contrast, adjusted for multiple comparisons, or used a hierarchy among outcomes is not reported in the registry record. The outcome names do not establish that interim statistical analyses were conducted. Any multiplicity procedure or rationale is likewise not reported in the registry record. Without this information and the individual estimates, it is not possible to assess how multiple outcomes or time points were handled.

Missing-data handling and analysis populations are also not reported in the registry record. Although 35 participants were enrolled, the record does not state the number with complete pre- and post-treatment scores, the number contributing to each treatment period, or how incomplete observations were treated. It does not identify an intention-to-treat, per-protocol, or other analysis population. In a crossover study, incomplete participation in one period can affect which comparisons are available; the record does not describe how that issue was addressed.

These omissions limit assessment of both bias and precision. They do not establish that data were missing or that any particular analysis was inappropriate; they mean that the registry record does not report the information needed to evaluate those possibilities.

11. 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 record reports no serious adverse events and no other adverse events in the listed groups. For the group titled Standard Then Alternative: High Dose, 0 serious events were reported among 8 at risk, and 0 other events among 8 at risk. For Alternative: High Dose Then Standard, the corresponding figures were 0 among 9 at risk for serious events and 0 among 9 at risk for other events. For High Dose Frequency Then Standard, they were 0 among 9 at risk for serious events and 0 among 9 at risk for other events. For Standard Then Alternative: High Dose Frequency, they were 0 among 8 at risk for serious events and 0 among 9 at risk for other events. Deaths are reported as 0 in each group.

These are the event counts and at-risk counts recorded for the listed groups. A zero count means no event was recorded in that group in the registry record; it does not show that an event is impossible or that risk is absent. The record does not provide additional detail about how adverse events were solicited, the observation period for safety reporting, or how the at-risk counts relate to treatment periods in the crossover design. The figures therefore describe the reported counts, not a comprehensive estimate of safety under all circumstances.

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

The registry record establishes that a randomized crossover study evaluated interactive book-reading regimens for word learning in Kindergarten children with SLI. It defines the primary outcome as a count of words known, based on whether a child’s definition met the study’s threshold for partial or complete accuracy. It also records the treatment sequences, the planned contrast in dose and reading frequency, and the investigators’ hypothesis favoring more frequent book reading over more repetitions within a book.

Those design and measurement details do not establish which regimen had better outcomes. A single numerical comparison of the primary outcome is not reported in the registry record, and the direction, size, and precision of a treatment contrast cannot be determined from the treatment descriptions or hypothesis. The record does not support a conclusion that one approach was superior or that the approaches were equivalent.

The absence of one reported comparison also does not establish that no analyses were performed. The registry record identifies 3 outcome measures and 3 analyses, but does not provide a single primary contrast that can be interpreted as the answer to the central question. Nor does it report sufficient analysis details to determine how repeated measurements, treatment sequence, missing data, or multiple outcomes were handled.

The adverse-event counts are zero in the listed groups, with the at-risk counts reported for each. These figures describe the registry record’s reported events; they do not establish that there is no risk. Likewise, enrollment of 35 participants does not reveal how many contributed to each outcome analysis or how precise any estimate would be.

The appropriate reading is therefore limited: the record describes a trial designed to study how word exposures are arranged during interactive book reading, but does not report enough numerical outcome information to quantify or compare the word-learning results. The study hypothesis is not a substitute for an observed treatment estimate.

13. Why This Trial Matters Statistically

This trial is statistically interesting because it asks about the arrangement of exposure, not simply whether children receive an intervention or no intervention. The standard and alternative regimens vary dose and dose frequency, while the stated objective is to achieve the appropriate intensity of 36 exposures. Separating the number of repetitions within a book from how often the book is read raises a design question about which component or combination is associated with change in the word-learning score.

The crossover structure creates an opportunity to compare treatment conditions within participants, but also makes order and period important. A treatment received first may not be directly comparable with the same treatment received later if outcomes change over time or if an earlier condition influences a later one. The registry record lists sequences in both orders for standard and alternative regimens, but does not report how these features were incorporated into the analysis. That makes the design a useful reminder that randomization alone does not describe every modeling decision needed for repeated treatment periods.

The endpoint also illustrates how measurement rules shape a statistical result. The study counted words with partially or completely accurate definitions as known, while excluding vague definitions and correct sentence use. The resulting mean is therefore tied to a specific operational definition of word knowledge. The score’s range and scoring threshold help clarify what a mean difference would represent, if a contrast were reported.

Finally, the record distinguishes a hypothesis and planning assumptions from findings. It describes an expectation about book-reading frequency and planning illustrations based on an observed effect, but neither constitutes an observed comparative result. Because a single numerical primary comparison is not reported in the registry record, the central statistical lesson is the importance of transparent outcome estimates, uncertainty, and analysis details alongside a well-described design.

14. 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 does not report a single numerical primary-outcome comparison, so the treatment effect and its precision cannot be evaluated. It identifies multiple categories or time points for the primary outcome, but does not provide the estimates needed to understand how results differed across those categories or times. The number of enrolled participants is reported as 35, but the number analyzed for each comparison is not reported in the registry record.

Important crossover details are also absent. The record does not report whether there was a washout, how treatment period and sequence were modeled, or how potential carryover was considered. It does not identify who was masked, describe the randomization procedure, or report adherence and completion for each treatment period. These are limitations of what can be assessed from the registry record; they do not prove that the study omitted these procedures.

The statistical analysis plan, including the model, contrast definition, missing-data approach, analysis population, and any multiplicity adjustment, is not reported in the registry record. The record names secondary outcomes and gives counts of outcome measures and analyses, but does not clarify the planned relationship among them. This makes it difficult to assess whether the reported analyses align with a prespecified primary question.

The adverse-event counts are reported as zero, but further safety-collection details and observation periods are not reported. The listed at-risk counts alone do not establish the completeness of reporting or the duration of observation. Taken together, these reporting gaps prevent a full assessment of the magnitude, precision, robustness, and safety interpretation of the study’s findings from the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Accelerating Word Learning in Children With Language Impairment — NCT01829360.
• Registry record last updated 2019-11-14; status last verified 2019-10.
• Results first posted 2019-11-14.
• 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.

18. Record Summary

NCT01829360, titled Accelerating Word Learning in Children With Language Impairment, is a completed randomized, single-masked crossover study sponsored by the University of Kansas. The official title is Interactive Book Reading to Accelerate Word Learning by Children With SLI. The condition is Specific Language Impairment, and enrollment is recorded as 35. The study start is listed as 2013-03 and primary completion as 2018-08; phase is recorded as NA.

The behavioral intervention is interactive book reading, also described as dialogic reading and shared book reading. The four listed sequences combine the standard regimen, dose 6 x dose frequency 6, with alternatives emphasizing high dose, dose 9 x dose frequency 4, or high dose frequency, dose 4 x dose frequency 9. Treatment is described as lasting 10 to 23 sessions, approximately 5 to 12 weeks.

The primary outcome is change in words known from pre- to post-treatment, summarized as a mean with standard error. The registry record defines the scoring and lists secondary outcomes Interim Definition and Interim Naming. It does not report a single numerical primary-outcome comparison, and details of the statistical plan, missing-data handling, and analysis populations are not reported in the registry record.