| PRL | Polo Response Latency | ms | 2003 | Time from the end of a Marco call to the onset of a Polo response, measured by pressure-plate microphones. Lower is better for an evader, because a quick, short Polo gives the Marco less time to locate the source. |
| PRC | Polo Response Compliance | % | 2016 | Share of Polo responses that began within the 0.6-second window set by Article 2.2.2. |
| MCV | Marco Call Volume | dB SPL @ 1 m | 2003 | Sound pressure level of the Marco call measured 1.000 m from the caller's mouth. Legal range: 65–95 dB. |
| MCD | Marco Call Duration | s | 2003 | Duration of the call from the onset of “Ma” to the end of “-co”. Maximum 1.4 s. |
| BE | Bearing Error | ° | 2011 | Angle between the Marco's lunge vector and the bearing of the nearest evader at the moment of the call, computed by Hawk-Ear. |
| CPT | Calls per Tag | calls | 1974 | Total Marco calls divided by tags made. The most direct measure of a Marco's efficiency. |
| xT | Expected Tags | tags | 2011 | Tags a Marco would be expected to make, given the distances, acoustics and evader speeds measured by Hawk-Ear. |
| ES | Evasion Seconds | s | 1931 | Mean time an evader survived per chukka. An evader who is never tagged scores 180. |
| FOW | Fish Out of Water | count | 1951 | Infractions for leaving the water for more than 3.0 seconds. |
| SE | Splash Entropy | bits | 2011 | Shannon entropy of the surface-disturbance signal around an athlete. A quieter swimmer gives a Marco less to hear. |
| WI | Fingertip Wrinkle Index | 0–10 | 2023 | Degree of fingertip wrinkling, measured by capacitive gloves at the end of each chukka. Used as a fatigue marker. |
| HRP | Peak Heart Rate | bpm | 2016 | Highest heart rate recorded by chest strap during the championship. |
| Elo | FIMP World Ranking (Elo) | points | 1931 | Rating calculated from every championship placing since 1931, with final margins weighted. Separate rankings for Indoor and Outdoor; results from the unified era count towards both. |
