Contents
How is a fixed effect meta-analysis calculated?
A fixed-effect meta-analysis using the inverse-variance method calculates a weighted average as: where Yi is the intervention effect estimated in the ith study, SE i is the standard error of that estimate, and the summation is across all studies.
What kind of Statistics are used in a meta-analysis?
The two summary statistics commonly used for meta-analysis of continuous data are the mean difference (MD) and the standardized mean difference (SMD). Other options are available, such as the ratio of means (see Chapter 6, Section 6.5.1 ).
What are two approaches to meta-analysis of time to event outcomes?
Two approaches to meta-analysis of time-to-event outcomes are readily available to Cochrane Review authors. The choice of which to use will depend on the type of data that have been extracted from the primary studies, or obtained from re-analysis of individual participant data.
Why are some studies excluded from a meta-analysis?
The standard practice in meta-analysis of odds ratios and risk ratios is to exclude studies from the meta-analysis where there are no events in both arms. This is because such studies do not provide any indication of either the direction or magnitude of the relative treatment effect.
How to simulate survival data with the SIM survdata function?
The coefficients and the covariates together form values of the linear predictor, contained in the xb attribute, and exponentiated values of the linear predictor, contained in the exp.xb attribute: In the course of generating simulations, the flexible-hazard method requires expressing each individual observation’s survivor function.
When to use a summary statistic in a meta-analysis?
The selection of a summary statistic for use in meta-analysis depends on balancing three criteria (Deeks 2002). First, we desire a summary statistic that gives values that are similar for all the studies in the meta-analysis and subdivisions of the population to which the interventions will be applied.
Do you do a meta-analysis in a systematic review?
Do not do a meta-analysis. A systematic review need not contain any meta-analyses. If there is considerable variation in results, and particularly if there is inconsistency in the direction of effect, it may be misleading to quote an average value for the intervention effect.
Is the Peto method more biased than other methods?
For rare events, the Peto method has been observed to be less biased and more powerful than other methods. Variation across studies (heterogeneity) must be considered, although most Cochrane Reviews do not have enough studies to allow for the reliable investigation of its causes.