Meta-analysis:
Effect size: The effect size is a value which reflects the magnitude of the treatment effect or the strength of a relationship between two variables, is the unit of currency in meta-analysis. (Black square)
Precision: It is the C.I. of the effect-size.
Study weight: It is the weight assigned to each study. The weight assigned is dependent on the precision. (The larger the square the larger the study weight)
Summary effect: It is the weighted mean of the individual effects. The mechanism used to assign the weights depends on our assumptions about the distribution of effect sizes from which the studies were sampled. Under the fixed-effect model, the assumption is that all the studies in the analysis share the same true effect size. The summary effect then is the estimate of this common effect size. Under the random-effect model, the assumption is true effect size varies from study to study. The summary effect here will be the mean of the distribution of effect sizes. (Diamond)
Precision: The location of the diamond represents the effect size. Its width reflects the precision of the estimate.
In fixed effect model: the weight of individual study is reciprocal of that study’s variance
In Random-effect model: We assume that the true effect is normally distributed
To be continued...
PSM / COMMUNITY MEDICINE by Dr Abhishek Jaiswal is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Based on a work at learnpsm@blogspot.com.
Permissions beyond the scope of this license may be available at jaiswal.fph@gmail.com.
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