為何會有這段影片檔
2014年9月時參加實證醫學會主辦的工作坊，其中一項作業是抽一個主題上台試教，題目都是實證有關的專有名詞，例如：盲性、隨機分派、異質性等。我抽到的題目就是「Fixed Effect Model and Random Effects Model」，聽說是籤王等級的題目。本來是兩天的工作坊，且第二天就要上台試教的，恰巧碰到颱風來攪局，變成回家自己錄影交作業。
謝謝這個颱風，讓我回家可以慢慢搞清楚這難懂的題目……
Youtube影片
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固定效應模型與隨機效應模型的比較
講者：門諾醫院 李坤峰
介紹
本文介紹了兩種統計分析模型:固定效應模型(Fixed Effect Model)和隨機效應模型(Random Effect Model)。這兩種模型常用於醫學研究中的統合分析(Meta-analysis)。
固定效應模型
固定效應模型假設所有研究都有相同的真實效果(True effect)。它主要考慮研究內的變異量,權重與病人數量成正比。
隨機效應模型
隨機效應模型假設每個研究都有其獨特的真實效果。它考慮研究內和研究間的變異量,目的是求取真實效果的平均值。
兩種模型的比較
- 變異量:固定效應模型只考慮研究內變異量,隨機效應模型考慮研究內和研究間變異量。
- 權重:隨機效應模型給予小型研究較大的權重。
- 95%信賴區間:隨機效應模型通常有較寬的信賴區間。
模型的應用
選擇模型時需考慮以下因素:
- 研究設計:若研究間方法相似,可選擇固定效應模型;若差異較大,則選擇隨機效應模型。
- 異質性:高異質性通常適合使用隨機效應模型。
- 結果解讀:需同時考慮異質性、所選模型和統計結果。
Fixed Effect Model vs Random Effect Model in Meta-Analysis
By Dr. Lee from Mendo Hospital
Introduction
This article discusses two statistical models used in meta-analysis: the Fixed Effect Model and the Random Effect Model. These models are important for analyzing data from multiple studies in medical research.
Fixed Effect Model
The Fixed Effect Model assumes:
- All studies have the same true effect
- Observed effects differ due to sampling error
- Differences between observed and true effects are sampling errors
The Fixed Effect Model is suitable for studies with similar sampling and methodologies. It gives more weight to studies with larger sample sizes.
Random Effect Model
The Random Effect Model assumes:
- Each study has a unique true effect
- We are estimating the average of these true effects
- There is uncertainty in this average, represented by a 95% confidence interval
The Random Effect Model is more appropriate when there are significant differences between studies.
Comparison of Models
Key differences between the models:
- Fixed Effect Model focuses on true effect, while Random Effect Model focuses on average effect
- Fixed Effect Model gives more weight to larger studies
- Random Effect Model considers both within-study and between-study variance
- Random Effect Model typically has wider confidence intervals
Interpretation and Application
When interpreting meta-analysis results:
- Consider study design similarities
- Evaluate heterogeneity between studies
- Be cautious with high heterogeneity results, especially if using Fixed Effect Model
Conclusion
Both Fixed Effect and Random Effect Models have their place in meta-analysis. The choice depends on study characteristics and research questions. Careful interpretation is crucial, especially when dealing with heterogeneous studies.
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