A/B Testing

The term ``A/B testing'' is widely used in internet industry, which actually refers to large-scale online randomized experiments. Like clinical trials, the primary goal of A/B testing is to estimate the average causal effect of a treatment or intervention. However, it has two distinct features: First, A/B testing is typically conducted in an online environment to compare different versions of a digital product. Technology companies such as Microsoft, Apple, Google, Baidu, Alibaba, ChatGPT, Meta, TikTok, Amazon, LinkedIn, Uber, Lyft, routinely employ A/B testing to assess if a change in their internet-based services or products leads to improved user engagement or increased revenue for decision making. Second, the scale of A/B testing is usually larger than clinical trials, often involving millions of users. Well-established companies might perform thousands of A/B testing each day.