heterogeneity
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More on means, less on dispersion
- =50% 不能区别坡度
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置信区间不能反应分散的取向,而是准确度。
- Predict interval: Mean 2x std Dev 是唯一能知道 effect vary
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Does effect vary at all? p value How much it cost -> more than 0 What proportion is real? I will get 70% discount How much does effect vary? Prediction interval how much will I pay -
Role of heterogeneity in meta-analysis:
- Narrow case v.s Wide case
- must study with means
terminology
I-Squared: From Calculation to Concept
: a measure of heterogeneity of results across studies