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arXiv · 2404.10381

Covariate Ordered Systematic Sampling as an Improvement to Randomized Controlled Trials

Deddy Jobson·Li Yilin·Naoki Nishimura·Yang Jie·Koya Ohashi·Takeshi Matsumoto
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Abstract

The Randomized Controlled Trial (RCT) or A/B testing is considered the gold standard method for estimating causal effects. Fisher famously advocated randomly allocating experiment units into treatment and control groups to preclude systematic biases. We propose a variant of systematic sampling called Covariate Ordered Systematic Sampling (COSS). In COSS, we order experimental units using a pre-experiment covariate and allocate them alternately into treatment and control groups. Using theoretical proofs, experiments on simulated data, and hundreds of A/B tests conducted within 3 real-world marketing campaigns, we show how our method achieves better sensitivity gains than commonly used variance reduction techniques like CUPED while retaining the simplicity of RCTs.

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Deddy Jobson, Li Yilin, Naoki Nishimura, Yang Jie, Koya Ohashi, Takeshi Matsumoto. 2024-04-16. Covariate Ordered Systematic Sampling as an Improvement to Randomized Controlled Trials. https://arxiv.org/abs/2404.10381

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