What is a moderator in a meta-analysis?
Meta-analysis Overview. Testing for moderators. A moderator is a third variable that conditions the relations between 2 others. Because effect sizes are the relations between 2 variables, any variable that predicts the effect sizes is a moderator.
What is the purpose of conducting a moderator analysis in a meta-analysis?
Moderator analysis: In the context of a meta-analysis, this refers to using some kind of method in an attempt to find and account for systematic differences in the size of the effect or outcome that is being meta-analyzed.
What is meta-regression analysis?
Meta-regression is defined to be a meta-analysis that uses regression analysis to combine, compare, and synthesize research findings from multiple studies while adjusting for the effects of available covariates on a response variable.
What is meta-regression used for?
Meta-regression is used to create a model describing the linear relationship between (both continuous and categorical) study-level covariates and the effect size (Hartung et al., 2008; Borenstein et al., 2009; Higgins and Green, 2011). If no predictors have been entered yet, you can add them now.
How many studies do you need for meta regression?
Meta-regression should generally not be considered when there are fewer than ten studies in a meta-analysis. Meta-regressions are similar in essence to simple regressions, in which an outcome variable is predicted according to the values of one or more explanatory variables.
Why do we use moderation analysis?
A moderator analysis is used to determine whether the relationship between two variables depends on (is moderated by) the value of a third variable. We use the standard method of determining whether a moderating effect exists, which entails the addition of an (linear) interaction term in a multiple regression model.
How do you interpret moderation effects?
Moderation effects are difficult to interpret without a graph. It helps to see what is the effect of the independent value at different values of the moderator. If the independent variable is categorical, we measure its effect through mean differences, and those differences are easiest to see with plots of the means.
Can you do meta regression in RevMan?
When a meta-analysis includes many studies, meta-regression analyses can include more than one domain (e.g. both allocation concealment and blinding). Within a fixed-effect meta-analysis framework, such tests are available in RevMan 5.
What are moderator variables?
Moderator variable. A moderator variable is, in general terms, a qualitative (e.g., sex, race, class) or quantitative (e.g., level of reward) variable that affects the direction and/or strength of the relation between dependent and independent variables.
How do moderator variables impact results?
Moderator variables are a type of variable that affects the direction and/or strength of a relationship between an independent and dependent variable. They can impact results by strengthening or weakening a relationship which would exist at a different level if it were not for the moderator. An example of this might exist while training a pet.
What is moderator in statistics?
Moderation (statistics) In statistics and regression analysis, moderation occurs when the relationship between two variables depends on a third variable. The third variable is referred to as the moderator variable or simply the moderator.
How to test for moderation?
Steps for moderation analysis Compute the interaction term XZ=X*Z. Fit a multiple regression model with X, Z, and XZ as predictors. Test whether the regression coefficient for XZ is significant or not. Interpret the moderation effect. Display the moderation effect graphically.