R: Select Parameters for Tree

tree.control {tree} | R Documentation

## Select Parameters for Tree

### Description

A utility function for use with the `control` argument of `tree`.

### Usage

    tree.control(nobs, mincut = 5, minsize = 10, mindev = 0.01)

### Arguments

`nobs` | The number of observations in the training set.
`mincut` | The minimum number of observations to include in either child node. This is a weighted quantity; the observational weights are used to compute the ‘number’. The default is 5.
`minsize` | The smallest allowed node size: a weighted quantity. The default is 10.
`mindev` | The within-node deviance must be at least this times that of the root node for the node to be split.

### Details

This function produces default values of `mincut` and `minsize`, and ensures that `mincut` is at most half `minsize`.

To produce a tree that fits the data perfectly, set `mindev = 0` and `minsize = 2`, if the limit on tree depth allows such a tree.

### Value

A list:

`mincut` | The maximum of the input or default `mincut` and 1
`minsize` | The maximum of the input or default `minsize` and 2.
`nmax` | A estimate of the maximum number of nodes that might be grown.
`nobs` | The input `nobs`.

### Note

The interpretation of `mindev` given here is that of Chambers and Hastie (1992, p. 415), and apparently not what is actually implemented in S. It seems S uses an absolute bound.

### Author(s)

B. D. Ripley

### References

Chambers, J. M. and Hastie, T. J. (1992) Statistical Models in S. Wadsworth & Brooks/Cole.

### See Also

`tree`

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