perturb {dembase} | R Documentation

## Generate demographic array consisting of random values.

### Description

If `object` has a dimension with `dimtype` `"Iterations"`, then `perturb` returns `n` randomly-selected iterations. Otherwise, it fits a log-linear model to the data and uses this to randomly generate `n` iterations. The log-linear model by default contains 2-way interactions; higher or lower values can be specified via `order`.

### Usage

    perturb(object, n = 1L, order = 2L, phi = 1, subtotals = NULL)

    ## S4 method for signature 'DemographicArray'
    perturb(object, n = 1L, order = 2L, phi = 1, subtotals = NULL)

### Arguments

`object` | Object of class `DemographicArray`.
`n` | Number of iterations to generate.
`order` | Order of interations used in log-linear models.
`phi` | A positive number governing the amount of random noise: higher values imply more variation.
`subtotals` | Not implemented yet

### Details

Arguments `order` and `phi` only have an effect when a log-linear model is fitted - in other words, when `object` does not have dimtype `"Iterations"`.

`object` can contain missing values, though if a log-linear model is fitted, there must be sufficient observations for a model with order-way interations.

### Value

An object of the same class as `object`. If `n > 1`, the return value has a dimension with dimtype `"Iterations"`; otherwise it does not.

### See Also

The log-linear model is fitted using `loglm`.

### Examples

    library(demdata)
    x <- Values(VADeaths2)
    perturb(x)
    perturb(x, phi = 2) ## greater variance
    perturb(x, order = 1) ## log-linear model only includes main effects
    perturb(x, n = 2)
    x10 <- perturb(x, n = 10)
    perturb(x10, n = 2)  ## iterations selected, rather than generated

[Package dembase version 0.0.0.119 Index]