A proxy measure is a substitute or alternative method used to estimate, approximate, or represent something that cannot be directly measured. It's an indirect way of measuring something by using another variable as a stand-in for what you want to know. Proxy measures are often used when the direct measurement of a particular characteristic is difficult, expensive, or impossible due to various constraints such as time, resources, or accessibility. These measures can provide valuable insights into underlying phenomena and help make informed decisions even if they're not perfect representations of what they aim to measure.