Fig. 2.

Subgroups of participants identified through classification tree analysis and the proportion of the consented participants by referral source, age (younger than 75 yrs old or not), and gender, the three most influential factors in the likelihood of consent. Race and ethnicity were not sufficiently influential to be included. All modeling done using R package rpart. The minimum number of participants to split the node was set to 100 and complexity parameter to 0.01.