The document discusses how to effectively test business signage by applying a theory. It recommends identifying a specific problem to solve, like increasing theatre subscriptions rather than general sales. The solution should target this problem with a clear call to action, like urging subscriptions. Metrics like subscription rates before and after can measure the sign's effectiveness by comparing the increase. The example theatre sign promoting subscriptions and benefits increased subscriptions by 125 people. Testing different digital signs allows comparing multiple low-cost solutions.