Humans naturally filter raw sensory input. You don’t really see everything in front of you, your brain reduces the vast amount of visual information to simplified forms, re-uses stale input, and other tricks to keep the bandwidth down. We run the same risk in organizations, relying on low-quality proxies of information instead of actual empirical data.
For example, an industry certification is a proxy for an engineer’s experience and ability. But it’s not a very good proxy, it may not amount to much more than an attendance certificate. Velocity is a proxy for value produced by a team. Estimates are a proxy for learning.
Gerald Weinberg once wrote that every crisis is the end of an illusion. Proxies of any sort will cause information distortion, reducing accuracy to at least some degree. In the worst (and unfortunately common) case, this can cause a full-on illusion.
Wherever you can, you want to the real data, not the proxy. Actual capability, not a piece of paper. Actual shipping software that generates value, not numbers on a spreadsheet. Actual users in their native habitat, not a watered-down version in a memo or on a story card. You want the real stuff, you want Actuals, not Proxies.