grad-meta-analysis
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Chinese後設分析 (Meta-Analysis)
元分析 (Meta-Analysis)
Overview
概述
Meta-analysis statistically combines effect sizes from multiple independent studies to produce a pooled estimate with greater precision and generalizability. It quantifies between-study heterogeneity and tests for publication bias, providing a rigorous evidence synthesis that goes beyond narrative literature reviews.
元分析通过统计学方法整合多项独立研究的效应量,生成合并估计值,具备更高的精确性和普适性。它量化研究间的异质性并检验发表偏倚,提供了比叙述性文献综述更严谨的证据整合方式。
When to Use
适用场景
- Synthesizing quantitative findings from multiple studies on the same research question
- Resolving conflicting results across studies
- Estimating an overall effect size with tighter confidence intervals
- Identifying moderators that explain heterogeneity across studies
- 针对同一研究问题,整合多项研究的量化结果
- 解决不同研究间的结果冲突
- 估计具有更窄置信区间的整体效应量
- 识别可解释研究间异质性的调节变量
When NOT to Use
不适用场景
- Studies are too heterogeneous in constructs, measures, or populations to combine meaningfully
- Fewer than 5 studies are available (pooled estimates become unreliable)
- Primary studies have fundamentally different research designs (mixing RCTs with observational)
- The research question is qualitative or conceptual rather than quantitative
- 研究在概念、测量方法或研究人群上差异过大,无法进行有意义的整合
- 可用研究数量少于5项(合并估计值会变得不可靠)
- 原始研究的设计存在本质差异(如将随机对照试验与观察性研究混合)
- 研究问题为定性或概念性,而非定量
Assumptions
假设前提
IRON LAW: A meta-analysis is only as good as the studies it includes —
garbage in, garbage out. Publication bias inflates pooled effect sizes
because non-significant findings go unpublished.Key assumptions:
- Studies estimate the same underlying construct (conceptual homogeneity)
- Effect sizes are statistically independent (one effect per study, or use multilevel models)
- Study-level moderators are coded reliably and without bias
- The search strategy captures the relevant population of studies (no systematic omission)
铁律:元分析的质量取决于纳入研究的质量——输入垃圾,输出垃圾。发表偏倚会夸大合并效应量,因为无显著性结果的研究往往不会被发表。核心假设:
- 所有研究均估计同一潜在概念(概念同质性)
- 效应量在统计学上相互独立(每项研究仅提取一个效应量,或使用多水平模型)
- 研究层面的调节变量编码可靠且无偏倚
- 检索策略覆盖了相关研究群体(无系统性遗漏)
Methodology
方法流程
Step 1 — Extract and Code Effect Sizes
步骤1 — 提取并编码效应量
Convert study findings to a common effect size metric (Cohen's d, Hedges' g, r, OR). Code study-level moderators (sample size, design, context). See for conversion formulas.
references/将研究结果转换为通用的效应量指标(Cohen's d、Hedges' g、r、OR)。编码研究层面的调节变量(样本量、研究设计、研究场景)。转换公式可参考目录。
references/Step 2 — Choose Fixed-Effect vs Random-Effects Model
步骤2 — 选择Fixed-effect模型 vs Random-effects模型
Fixed-effect assumes one true effect; random-effects assumes effects vary across studies. If studies span different populations or contexts, random-effects is almost always appropriate.
Fixed-effect模型假设存在唯一真实效应;Random-effects模型假设效应在不同研究间存在差异。若研究涵盖不同人群或场景,Random-effects模型几乎总是更合适的选择。
Step 3 — Assess Heterogeneity
步骤3 — 评估异质性
Compute Q statistic (test of homogeneity), I² (proportion of variance due to heterogeneity), and τ² (between-study variance). I² > 75% indicates substantial heterogeneity warranting moderator analysis.
计算Q统计量(同质性检验)、I²(异质性导致的方差占比)和τ²(研究间方差)。I² > 75%表明存在显著异质性,需进行调节变量分析。
Step 4 — Test for Publication Bias and Report
步骤4 — 检验发表偏倚并撰写报告
Use funnel plot, Egger's regression test, and trim-and-fill method. Report pooled effect, CI, prediction interval, and results of bias assessment.
使用漏斗图、Egger回归检验和剪补法(trim-and-fill)。报告合并效应量、置信区间(CI)、预测区间以及偏倚评估结果。
Output Format
输出格式
markdown
undefinedmarkdown
undefinedMeta-Analysis: [Research Question]
元分析:[研究问题]
Study Inclusion
研究纳入情况
| Criterion | Value |
|---|---|
| Studies included (k) | xx |
| Total sample size (N) | xxxx |
| Effect size metric | [d / r / OR] |
| 标准 | 数值 |
|---|---|
| 纳入研究数量(k) | xx |
| 总样本量(N) | xxxx |
| 效应量指标 | [d / r / OR] |
Pooled Effect Size
合并效应量
| Model | Effect | 95% CI | z | p-value |
|---|---|---|---|---|
| Fixed-effect | x.xx | [x.xx, x.xx] | x.xx | x.xx |
| Random-effects | x.xx | [x.xx, x.xx] | x.xx | x.xx |
| 模型 | 效应值 | 95% CI | z | p值 |
|---|---|---|---|---|
| Fixed-effect | x.xx | [x.xx, x.xx] | x.xx | x.xx |
| Random-effects | x.xx | [x.xx, x.xx] | x.xx | x.xx |
Heterogeneity
异质性分析
| Statistic | Value | Interpretation |
|---|---|---|
| Q | x.xx (p = x.xx) | [significant/not] |
| I² | x.xx% | [low/moderate/high] |
| τ² | x.xx | [between-study variance] |
| 统计量 | 数值 | 解释 |
|---|---|---|
| Q | x.xx (p = x.xx) | [显著/不显著] |
| I² | x.xx% | [低/中/高] |
| τ² | x.xx | [研究间方差] |
Publication Bias
发表偏倚检验
| Test | Result | Interpretation |
|---|---|---|
| Funnel plot | [symmetric/asymmetric] | [bias suspected?] |
| Egger's test | p = x.xx | [significant?] |
| Trim-and-fill | adjusted effect = x.xx | [studies imputed: x] |
| 检验方法 | 结果 | 解释 |
|---|---|---|
| 漏斗图 | [对称/不对称] | [是否怀疑存在偏倚?] |
| Egger检验 | p = x.xx | [是否显著?] |
| 剪补法 | 调整后效应值 = x.xx | [填补研究数量: x] |
Limitations
局限性
- [Note any assumption violations]
undefined- [注明任何违反假设的情况]
undefinedGotchas
注意事项
- Combining apples and oranges: statistically possible but conceptually meaningless if constructs differ
- Random-effects models give more weight to small studies, which are often lower quality
- I² depends on precision of included studies; low I² with imprecise studies does not mean homogeneity
- Funnel plot asymmetry can be caused by factors other than publication bias (small-study effects)
- File-drawer problem: unpublished null results are systematically missing
- Moderator analyses with many subgroups and few studies per subgroup are underpowered and unreliable
- 不当整合:若研究概念不同,即使统计上可行,概念层面也毫无意义
- Random-effects模型会赋予小样本研究更高权重,而这类研究通常质量较低
- I²的大小取决于纳入研究的精确性;若研究本身精度低,I²值小并不代表同质性
- 漏斗图不对称可能由发表偏倚以外的因素导致(小样本效应)
- 文件抽屉问题:未发表的无效结果被系统性遗漏
- 若调节变量分析包含多个亚组且每个亚组的研究数量较少,统计效力不足,结果不可靠
References
参考文献
- Borenstein, M., Hedges, L. V., Higgins, J. P. T., & Rothstein, H. R. (2009). Introduction to Meta-Analysis. Wiley.
- Higgins, J. P. T., & Thompson, S. G. (2002). Quantifying heterogeneity in a meta-analysis. Statistics in Medicine, 21(11), 1539-1558.
- Rothstein, H. R., Sutton, A. J., & Borenstein, M. (2005). Publication Bias in Meta-Analysis. Wiley.
- Borenstein, M., Hedges, L. V., Higgins, J. P. T., & Rothstein, H. R. (2009). Introduction to Meta-Analysis. Wiley.
- Higgins, J. P. T., & Thompson, S. G. (2002). Quantifying heterogeneity in a meta-analysis. Statistics in Medicine, 21(11), 1539-1558.
- Rothstein, H. R., Sutton, A. J., & Borenstein, M. (2005). Publication Bias in Meta-Analysis. Wiley.