Table 4 Concordance indices, measures of explained variation, and Bayesian information criterion for American Joint Committee on Cancer 7th and 8th edition staging systems compared to the Vanderbilt staging system for retroperitoneal sarcoma

Gönen & Heller’s K

0.5324

0.6116^a

0.6299^b

0.6373^b

0.0016

Harrell’s c

0.5426

0.6189^a

0.6305^b

0.6495^c

0.0002

Somer’s D

0.1040

0.2866^a

0.3072^a

0.3315^b

0.0067

ρ ² _k

0.0837

0.2113^a

0.2347^b

0.2614^c

0.0003

R ²

0.05536

0.1491^a

0.1745^b

0.1859^b

0.0001

BIC

43374.411

43014.326

42934.846

42832.904