BART Procedure

TREEPRIOR Statement

TREEPRIOR <prior-options>;

The TREEPRIOR statement enables you to specify the regularization prior for the sum-of-trees ensemble. For more information about the regularization prior, see the section Tree Prior. You can use the following prior-options to specify the regularization prior for the sum-of-trees ensemble:

DEPTHBASE=number

specifies the base probability for splitting an internal node as a function of its depth from the root. A larger base probability value makes splitting a node more likely. The value of number must be between 0 and 1, exclusive.

By default, DEPTHBASE=0.95.

DEPTHPOWER=number

specifies the power parameter to be used to compute the probability of splitting an internal node as a function of its depth from the root. A larger depth power value decreases the probability of splitting a node. The value of number must be positive.

By default, DEPTHPOWER=2.

PPRUNE=number

specifies the probability of sampling the operation of pruning a terminal node for the tree sampling algorithm. The value of number must be between 0 and 1, exclusive, and if you specify both the PSPLIT= and PPRUNE= options, their values must sum to 1. If you specify the PSPLIT= option but not the PPRUNE= option, the PPRUNE= option is set to 1 minus the PSPLIT= option value.

By default, PPRUNE=0.5.

PSPLIT=number

specifies the probability of sampling the operation of splitting a terminal node for the tree sampling algorithm. The value of number must be between 0 and 1, exclusive, and if you specify both the PSPLIT= and PPRUNE= options, their values must sum to 1. If you specify the PPRUNE= option but not the PSPLIT= option, the PSPLIT= option is set to 1 minus the PPRUNE= option value.

By default, PSPLIT=0.5.

Last updated: May 14, 2026