Vocabulary Improvement Program for English Language Learners and Their Classmates (VIP)

A group of closely related outcomes.

A summary of the effectiveness of an intervention in an outcome domain, based on the quality of research, the statistical significance of findings, the magnitude of findings, and the consistency of findings across studies.

Positive:  strong evidence that intervention had a positive effect on outcomes.

Potentially Positive:  evidence that intervention had a positive effect on outcomes with no overriding contrary evidence.

Mixed:  evidence that intervention’s effect on outcomes is inconsistent.

No Discernible:  no evidence that intervention had an effect on outcomes.

Potentially Negative:  evidence that intervention had a negative effect on outcomes with no overriding contrary evidence.

Negative:  strong evidence that intervention had a negative effect on outcomes.

For more, please see the WWC Glossary entry for rating of effectiveness.

The number of studies that met WWC design standards and provide evidence of effectiveness. Selecting an item below will display all studies that met WWC design studies in the domain. Selecting a study citation will take you to more information on that study and its findings.

For more, please see the WWC Glossary entry for study rating.

Grades of the students examined in the studies that met WWC design standards, which may not reflect the full range of grades for which the intervention may be used.

The number of students included in the studies that met WWC design standards.

The sample size for the studies that met WWC design standards.

An indicator of the effect of the intervention, the improvement index can be interpreted as the expected change in percentile rank for an average comparison group student if that student had received the intervention.

For more, please see the WWC Glossary entry for improvement index.

The indicator represents the highest level of similarity found between your students and each of the high-quality studies of the intervention. Three filled in ovals indicates that at least one study that met standards was conducted on students very similar to yours. Clicking on the indicator for a study will provide information on the similarity for each of the characteristics you selected.