What Works Clearinghouse



How to Find What Works

How to Find What Works| Glossary| Top

Step 1: Describe what you are looking for.

In the left hand search menu, select a topic or outcome based on your needs and interests. For example, if you are looking to improve language development in English language learners, select “English Language Learners” under Topics/Outcome Domains.

Topics are defined by a group of related student outcomes or outcome domains. This is indicated in the menu by the expand image image next to the topic name. Click the expand image image to see the topic's associated outcome domains. If you are only interested in one of these outcome domains, you can select just the one of interest.

Each time you make a selection, your search results are updated. Once you select a topic or outcome domain, you will be able to further filter your search results on grade, effectiveness, level of evidence, and delivery method.

Please see the Glossary for the definitions of terms used.

How to Find What Works| Glossary| Top

Step 2: View your results.

Results are ordered by outcome domains and show you what the research indicates about interventions’ evidence of effectiveness and also the quality and extent of this evidence.

Use the “Jump to findings for:” menu to go to a table of results for an outcome.

Each table can be sorted by improvement index (the default), by intervention name, effectiveness rating, and by extent of evidence for an intervention’s effectiveness.

The name of the intervention links you to the detailed report. The topic name links you to more information about that topic.

Select the “Research Details” tab to see the research details table. This table gives you more information about the research the WWC reviewed for an intervention report.

  • You can enlarge the view of this table by clicking and dragging the bottom right corner of the table.
  • Clicking an underlined column heading sorts the table by that column's data.
  • If you would like to interact with the data more, you can export it as text or as a comma-separated values file.
  • Use the Full Screen View & Print button, to view the table in its own window and print it from there.

Please see the Glossary for the definitions of terms used.

How to Find What Works| Glossary| Top

Step 3: Revise, review, and repeat.

To refine your results, continue to add or remove filters by checking or unchecking the check boxes in the menu. You can also remove filters using the links right above the results section.

The numbers in parenthesis next to a filter option indicate the number of interventions you would add or subtract by using or not using the filter.

To start a new search, use the “Reset Search” link in the left hand menu.

How to Find What Works| Glossary| Top

 

Glossary terms for Find What Works

For more WWC terms, see the full glossary.
delivery method
The method by which an intervention was delivered: individual, small group, whole class, or whole school. An individual method means that students work independently or one-on-one with the teacher, paraprofessional, parent, or other service provider. Small group means that the intervention is delivered with students working in small groups that can be any size, with at least two students per group. For the whole class method, the intervention is delivered to an entire class a majority of the time. With a whole school method the intervention is provided school-wide, not as an individual classroom approach.

How to Find What Works| Glossary| Top

effectiveness rating
 

In intervention reports, the WWC rates the effects of an intervention in each outcome domain. The rating of effectiveness takes into account four factors:

  1. the quality of the research on the intervention
  2. the statistical significance of the research findings
  3. the size of the differences between participants in the intervention and comparison groups,
  4. the consistency in findings across studies

Effectiveness Rating Key
Positive effectsPositive:  strong evidence that intervention had a positive effect on outcomes.
Potentially positive effectsPotentially Positive:  evidence that intervention had a positive effect on outcomes with no overriding contrary evidence.
Mixed effectsMixed:  evidence that intervention’s effect on outcomes is inconsistent.
No discernible effectsNo Discernible:  no evidence that intervention had an effect on outcomes.
Potentially negative effectsPotentially Negative:  evidence that intervention had a negative effect on outcomes with no overriding contrary evidence.
Negative EffectsNegative:  strong evidence that intervention had a negative effect on outcomes.

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extent of evidence
 An indicator of how much evidence supports the findings in an intervention report.

The extent of evidence categorization for intervention reports focuses on the number and sizes of studies of the intervention in order to give an indication of how broadly findings may be applied to different settings. There are two extent of evidence categories: small and medium to large.
  • small: includes only one study, or one school, or findings based on a total sample size of less than 350 students and 14 classrooms (assuming 25 students in a class)
  • medium to large: includes more than one study, more than one school, and findings based on a total sample of at least 350 students or 14 classrooms

How to Find What Works| Glossary| Top

improvement index
 The expected change in percentile rank for an average comparison group student if the student had received the intervention. It is measured as the percentile difference between the intervention group mean the comparison group mean using the comparison group distribution. Improvement IndexIn this example, the estimated average impact of the intervention is a 0.4 standard deviation improvement in reading scores. An average comparison group student (at the 50th percentile) would be expected to have scored 0.4 standard deviations above the mean if he or she had received the intervention, or at the 66th percentile of students. The resulting improvement index is +16, corresponding to moving performance for the average student from the 50th to the 66th percentile of the comparison group distribution.

How to Find What Works| Glossary| Top

intervention
An educational program, product, practice, or policy aimed at improving student outcomes. 

How to Find What Works| Glossary| Top

meets evidence standards
The highest possible rating for a study reviewed by the WWC. Studies receiving this rating provide the highest degree of confidence that an observed effect was caused by the intervention. Only well-implemented randomized controlled trials and regression discontinuity designs that do not have problems with attrition may receive this highest rating.

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meets evidence standards with reservations
The middle possible rating for a study reviewed by the WWC. Studies receiving this rating provide a lower degree of confidence that an observed effect was caused by the intervention. Randomized controlled trials and regression discontinuity designs that are not as well implemented or have problems with attrition, along with strong quasi-experimental designs, may receive this rating.

How to Find What Works| Glossary| Top

outcome
Knowledge, skills, attitudes, and other desired benefits that are attained as a result of an activity. To examine the effectiveness of an intervention for the WWC, eligible research must compare the outcome for a group receiving the intervention to the outcome for a group not receiving the intervention. An outcome measure is an instrument, device, or method that provides data on the outcome. An outcome domain is a group of closely related outcome measures, believed to provide information on the same underlying skill or ability.

How to Find What Works| Glossary| Top

outcome domain
A group of closely-related outcomes. A domain is the organizing construct for a set of related outcomes through which studies claim effectiveness. For example, the WWC alphabetics domain within the Literacy topic includes the following outcomes: phonemic and phonological awareness, letter identification, print awareness, and phonics. In intervention reports and practice guides, the WWC assesses the rigor of evidence on the effectiveness of interventions within each domain identified in the review protocol. The intervention rating, improvement index, and extent of evidence are determined at the domain level.

How to Find What Works| Glossary| Top

topic
An outcome, population, or type of intervention studied by the WWC. Topics are defined by intended outcome (such as improving reading skills), intended population (such as English language learners), and types of interventions (such as education technology) that may improve outcomes for students.