2 Introduction

These lectures aim to explore the concept of cause and effect, a fundamental pursuit in science. At its core, we often ask whether X causes Y , and if so, by how much. The ideal way to address such questions is through a carefully designed experiment—one that is controlled and systematic.

In an experimental setting, the researcher typically has control over key aspects of the setup: assigning treatments, ensuring controls are in place, and accurately measuring outcomes. However, the luxury of conducting controlled experiments is often out of reach, especially for many real-world research questions.

This collection of lectures focuses on the challenge of causal inference in such situations, specifically when relying on observational data. The emphasis will be on intuitive and empirical approaches, rather than delving deeply into the theoretical foundations of causal inference.