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Weighting studies
More weight to the studies which give more information
• more participants, more events, narrower confidence interval
• calculated using the effect estimate and its variance
Inverse-variance method:
weight 1 1 variance of estimate SE2
pooled estimate  sum of (estimateweight) sum of weights
Steps in doing a meta‐analysis
1. do a basic literature search
2. define comparisons for your review
3. decide on the outcomes for each comparison
4. select a summary statistic for each comparison
5. write a protocol and register your study
6. do an extended literature search
7. assess the similarity of study results within each comparison
8. consider the reliability of the summaries
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PRECONGRESS COURSE 13 I BARCELONA, SPAIN – 1 JULY 2018 45