Goodness of fit of observed and predicted survival for four risk groups.

<p>The 138 patients who died from melanoma were divided into four groups (see <a href="http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.1001604#s3" target="_blank">Methods</a>) with increasing risk of death, as defined by the survival model. Subsequently, the risk thresholds of the four groups were applied to all the patients. The Kaplan-Meier estimates (step functions) and the predicted survival curves (smooth curves) from the survival model are depicted for these four groups. All four of the groups differed from each other significantly (all <i>p-</i>values<0.001 in the log-rank test comparing group 2 to group 1, group 3 to group 2, and group 4 to group 3).