Systematic Review« Back to Glossary Index
« Back to Glossary Index
Related Glossary Terms:
- Librarian/Information Specialist
- Trim-and-Fill MethodWhen publication bias is suspected in a systematic review, investigators may attempt to estimate the true intervention effect by removing, or trimming, small positive studies that do not have a negative study counterpart and then calculating a supposed true effect from the resulting symmetric funnel plot. The investigators then replace the positive studies they have removed and add hypothetical studies that mirror these positive studies to create a symmetric funnel plot that retains the new pooled effect estimate. This method allows the calculation of an adjusted confidence interval and an estimate of the number of missing trials.
- HeterogeneityDifferences among individual studies included in a systematic review, typically referring to study results; the terms can also be applied to other study characteristics.
- Inclusion CriteriaThe characteristics that define the population eligible for a study or that define the studies that will be eligible for inclusion in a systematic review.
- Funnel PlotA graphic technique for assessing the possibility of publication bias in a systematic review. The effect measure is typically plotted on the horizontal axis and a measure of the random error associated with each study on the vertical axis. In the absence of publication bias, because of sampling variability, the graph should have the shape of a funnel. If there is bias against the publication of null results or results showing an adverse effect of the intervention, one quadrant of the funnel will be partially or completely missing.