Computing ratios automatically converts power variables into ratio-scale measures.

Evidence

The same sort of thing occurs when one calculates ratios. For example, international conflict scholars often want to know the relative military capabilities or power of various states. They calculate the ratio of the military capabilities (e.g., the widely used CINC military capability variable from the Correlates of War project). No surprise, when one calculates a ratio the power variables are automatically converted into a ratio scale. This may not be invalid: 0.0 on power might be a real zero. — Gary Goertz, Social Science Concepts and Measurement, 833

Categorization

• XREF: The CINC variable is a workhorse in quantitative IR; this flags a hidden measurement assumption behind a huge literature.
• CANDY: Good trivia for a quant IR colleague: every CINC ratio study quietly asserts a true zero of national power.