Relative Loop Activity is an equation-based causal contribution diagnostic similar to Stella-style loop analysis. At each simulation step, the simulator holds one upstream variable at its prior value, re-evaluates the downstream equation, and measures that link's share of the downstream change. Link contributions are combined around each closed path with a geometric mean, then summarized over the selected horizon. The highest-scoring loop is set to 100; the others are shown relative to it. A value of 70 means roughly 70% of the top loop's measured activity. It is not a percent of GDP or a claim that one loop alone caused that share of the outcome.