R: Extract pathways in model graph

path {lava} | R Documentation

## Extract pathways in model graph

### Description

Extract all possible paths from one variable to another connected component in a latent variable model. In an estimated model the effect size is decomposed into direct, indirect and total effects including approximate standard errors.

### Usage

    ## S3 method for class 'lvm'
     path(object, to = NULL, from, all=FALSE, ...)
    ## S3 method for class 'lvmfit'
     effects(object, to, from, ...)

### Arguments

`object` | Model object (`lvm`)
`...` | Additional arguments to be passed to the low level functions
`to` | Outcome variable (string). Alternatively a formula specifying response and predictor in which case the argument `from` is ignored.
`from` | Response variable (string), not necessarily directly affected by `to`.
`all` | If TRUE all simple paths (in undirected graph) is returned on/off.

### Value

If `object` is of class `lvmfit` a list with the following elements is returned

`idx` | A list where each element defines a possible pathway via a integer vector indicating the index of the visited nodes.
`V` | A List of covariance matrices for each path.
`coef` | A list of parameters estimates for each path
`path` | A list where each element defines a possible pathway via a character vector naming the visited nodes in order.
`edges` | Description of 'comp2'

If `object` is of class `lvm` only the `path` element will be returned.

The `effects` method returns an object of class `effects`.

### Note

For a `lvmfit`-object the parameters estimates and their corresponding covariance matrix are also returned. The `effects`-function additionally calculates the total and indirect effects with approximate standard errors

### Author(s)

Klaus K. Holst

### See Also

`children`, `parents`

### Examples

    m <- lvm(c(y1,y2,y3)~eta)
    regression(m) <- y2~x1
    latent(m) <- ~eta
    regression(m) <- eta~x1+x2
    d <- sim(m,500)
    e <- estimate(m,d)

    path(Model(e),y2~x1)
    parents(Model(e), ~y2)
    children(Model(e), ~x2)
    children(Model(e), ~x2+eta)
    effects(e,y2~x1)
    ## All simple paths (undirected)
    path(m,y1~x1,all=TRUE)

[Package lava version 1.6.1 Index]