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The Conditional Random-Effects Variance Component in Meta-regressionPowerPoint Presentation

The Conditional Random-Effects Variance Component in Meta-regression

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The Conditional Random-Effects Variance Component in Meta-regression

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The Conditional Random-Effects Variance Component in Meta-regression

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The Conditional Random-Effects Variance Component in Meta-regression

Michael T. Brannick

Guy Cafri

University of South Florida

- What is the random-effects variance component (REVC)?
- What is the conditional random-effects variance component (CREVC)?
- Who cares? (Tells whether we are done!)

Fixed

Mixed

CREVC = 0

CREVC > 0

Point Estimators of the CREVC

Method of Moments (WLS)

Maximum Likelihood (iterated WLS)

Significance tests

Fixed chi-square

Random chi-square (2 of these)

Lower bound > 0 (3 of these)

Confidence Intervals (3 types)

ML, bootstrap, bootstrap adjusted

- Bias
- RMSE
- Type I error
- Power
- Coverage probability
- Width

- Effect size: d
- Conditions (based on literature)
- REVC: 0, .04, .10, .19, .35, .52
- Proportion A/C: 0, .02, .18, .50
- K studies: 13, 22, 30, 69, 112, 234
- Average N (skewed): 53, 231, 730

- Reps: 10k times each for 378 cells

Note: results are averages over cells

Method of moments is less biased than max like until k > 100

Meta-analysis results for one cell

(10k trials for each method)

Bias corrected bootstrap has best coverage; similar width

Coverage

Width

- Slight preference for method of moments WLS when k is small
- Use the fixed-effects chi-square for testing the CREVC
- Use the bias-corrected bootstrap for constructing confidence intervals

- Please indicate the uncertainty of the estimates when reporting a meta-analysis (confidence intervals and/or standard errors of parameter estimates)
- Free software:
- http://luna.cas.usf.edu/~mbrannic/files/meta/MetaRegsMB1.sas