Restricted-Round Performance and Winning Margins in Olympic Synchronised Diving, 2000–2024

Olympic synchronised diving begins with two restricted rounds assigned a degree of difficulty (DD) of 2.0, followed by free rounds whose scores combine difficulty and judged performance. This retrospective study examined 28 Olympic finals from 2000 to 2024: 224 pair performances and 1,200 round scores. The primary measure compared champion–runner-up relative margins between scoring blocks. Restricted-minus-free differences averaged 3.01 percentage points in platform (95% bootstrap CI 0.62 to 5.41) and 0.38 in springboard (?2.96 to 3.91). The pooled estimate was 1.69 (?0.46 to 3.84). A direct platform–springboard contrast, matched by Games and sex and summarised across seven Games, remained uncertain: 2.63 percentage points (95% t interval ?1.54 to 6.79). Champions outscored runners-up on restricted rounds in 27 finals, with a mean counted-award advantage of 0.62 (95% CI 0.47 to 0.78). No champion’s restricted dive fell below the descriptive 8.0 benchmark, compared with nine runner-up dives; these were not validated technical-error classifications. Perfect restricted scores would still have been insufficient to close the runner-up’s final deficit in 16 finals with free scores unchanged. An official-book audit confirmed all 176 Beijing 2008 round scores and recovered DD for its 112 free dives; six further round scores were checked against a national Olympic committee report. The remaining 640 free-dive DD values were not recovered. The four-final DD analysis is reported separately rather than extrapolated across Games. These results provide historical scoring benchmarks, not evidence that restricted dives independently cause or predict Olympic success. Data, source-specific verification records and executable code accompany the manuscript.