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predicted_samples

Draw new response values from the conditional distribution of the response

Description

Predicted values of the response (new response data) are drawn from the fitted model, created via simulate() (e.g. simulate.gam()) and returned in a tidy, long, format. These predicted values do not include the uncertainty in the estimated model; they are simply draws from the conditional distribution of the response.

Usage

predicted_samples(model, ...)

## S3 method for class 'gam'
predicted_samples(
  model,
  n = 1,
  newdata = NULL,
  seed = NULL,
  weights = NULL,
  ...
)

Arguments

`model`	a fitted model of the supported types
`...`	arguments passed to other methods. For `fitted_samples()`, these are passed on to `predict.gam()`.
`n`	numeric; the number of posterior samples to return.
`newdata`	data frame; new observations at which the posterior draws from the model should be evaluated. If not supplied, the data used to fit the model will be used for `newdata`, if available in `model`.
`seed`	numeric; a random seed for the simulations.
`weights`	numeric; a vector of prior weights. If `newdata` is null then defaults to `object[["prior.weights"]]`, otherwise a vector of ones.

Value

A tibble (data frame) with 3 columns containing the posterior predicted values in long format. The columns are

row (integer) the row of newdata that each posterior draw relates to,
draw (integer) an index, in range 1:n, indicating which draw each row relates to,
response (numeric) the predicted response for the indicated row of newdata.

Author(s)

Gavin L. Simpson

Examples

load_mgcv()

dat <- gamSim(1, n = 1000, dist = "normal", scale = 2)
m <- gam(y ~ s(x0) + s(x1) + s(x2) + s(x3), data = dat, method = "REML")

predicted_samples(m, n = 5, seed = 42)

## Can pass arguments to predict.gam()
newd <- data.frame(x0 = runif(10), x1 = runif(10), x2 = runif(10),
                   x3 = runif(10))

## Exclude s(x2)
predicted_samples(m, n = 5, newd, exclude = "s(x2)", seed = 25)

## Exclude s(x1)
predicted_samples(m, n = 5, newd, exclude = "s(x1)", seed = 25)

## Select which terms --- result same as previous
predicted_samples(m, n = 5, newd, seed = 25,
                  terms = c("s(x0)", "s(x2)", "s(x3)"))

gratia

Graceful 'ggplot'-Based Graphics and Other Functions for GAMs Fitted Using 'mgcv'

v0.6.0

MIT + file LICENSE

Authors

Gavin L. Simpson [aut, cre] (<https://orcid.org/0000-0002-9084-8413>), Henrik Singmann [ctb] (<https://orcid.org/0000-0002-4842-3657>)

Initial release

2021-04-17