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Power and sample size calculations for Mendelian randomization studies using one genetic instrument
Guy Freeman1, Benjamin J Cowling, C Mary Schooling
1School of Public Health, Li Ka Shing Faculty of Medicine, University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China and CUNY School of Public Health at Hunter College, New York, USA.
International Journal of Epidemiology
|August 13, 2013
Summary
Calculating sample sizes for Mendelian randomization studies is crucial for efficient design. New formulas simplify power and sample size calculations, offering a more straightforward approach than simulations for causal inference.
Area of Science:
- Epidemiology
- Statistical Genetics
Background:
- Mendelian randomization (MR) is a powerful method for causal inference in observational studies.
- Accurate sample size calculation is essential for designing efficient MR studies.
Purpose of the Study:
- To present formulas for calculating the statistical power and minimum sample size for MR studies.
- To provide a more straightforward alternative to simulation methods for power and sample size estimation.
Main Methods:
- Derivation of power and sample size formulas using asymptotic statistical theory.
- Application of formulas to example data and comparison with simulation results.
Main Results:
- Formulas for MR study power and minimum sample size are presented.
- Sample size is inversely proportional to the squared correlation between genetic instrument and exposure, and the squared effect size.
- Sample size is proportional to the residual variance of the outcome.
Conclusions:
- The derived formulas offer a simpler method for power and sample size calculations in MR studies.
- These calculations are vital for the efficient design of genetic epidemiology research.
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