# A Rule of Thumb for the Power Gain due to Covariate Adjustment in Randomized Controlled Trials with Continuous Outcomes

arXiv: https://arxiv.org/abs/2308.07330 · HTML: https://mlsanity.com/paper/2308.07330/

## Key facts

- Cited by 1 papers in the map (data through 14 Oct 2026).
- First posted on arXiv 9 Aug 2023.

## Built on by (most cited first, 1 of 1)

- [A Weighted Prognostic Covariate Adjustment Method for Efficient and Powerful Treatment Effect Inferences in Randomized Controlled Trials](https://mlsanity.com/paper/2309.14256/) (2023)

## Abstract (arXiv)

Randomized Controlled Trials (RCTs) often adjust for baseline covariates in order to increase power. This technical note provides a short derivation of a simple rule of thumb for approximating the ratio of the power of an adjusted analysis to that of an unadjusted analysis. Specifically, if the unadjusted analysis is powered to approximately 80%, then the ratio of the power of the adjusted analysis to the power of the unadjusted analysis is approximately 1 + frac12 R2, where R is the correlation between the baseline covariate and the outcome.