Measurement is a fundamental aspect of successful marketing campaigns. It involves quantifying key performance indicators like sales, leads, and revenue to track the performance of campaigns and understand the customer journey across different channels and devices. There are three key principles of good measurement: choosing the right KPIs, understanding the customer journey, and measuring KPIs for users along their journey. Marketing statistics provide insights to optimize campaigns and determine their success in meeting business objectives. Measurement research is important for improving products and services by understanding customer preferences and creating efficient marketing plans tailored to different channels.