Augment accepts a model object and a dataset and adds information about each observation in the dataset. Most commonly, this includes predicted values in the .fitted column, residuals in the .resid column, and standard errors for the fitted values in a .se.fit column. New columns always begin with a . prefix to avoid overwriting columns in the original dataset.

Users may pass data to augment via either the data argument or the newdata argument. If the user passes data to the data argument, it must be exactly the data that was used to fit the model object. Pass datasets to newdata to augment data that was not used during model fitting. This still requires that all columns used to fit the model are present.

Augment will often behavior different depending on whether data or newdata is specified. This is because there is often information associated with training observations (such as influences or related) measures that is not meaningfully defined for new observations.

For convenience, many augment methods provide default data arguments, so that augment(fit) will return the augmented training data. In these cases augment tries to reconstruct the original data based on the model object, with some varying degrees of success.

The augmented dataset is always returned as a tibble::tibble with the same number of rows as the passed dataset. This means that the passed data must be coercible to a tibble. At this time, tibbles do not support matrix-columns. This means you should not specify a matrix of covariates in a model formula during the original model fitting process, and that splines::ns(), stats::poly() and survival::Surv() objects are not supported in input data. If you encounter errors, try explicitly passing a tibble, or fitting the original model on data in a tibble.

We are in the process of defining behaviors for models fit with various na.action arguments, but make no guarantees about behavior when data is missing at this time.

# S3 method for mjoint
augment(x, data = x$data, ...)

Arguments

x

An mjoint object returned from joineRML::mjoint().

data

A data.frame() or tibble::tibble() containing the original data that was used to produce the object x. Defaults to stats::model.frame(x) so that augment(my_fit) returns the augmented original data. Do not pass new data to the data argument. Augment will report information such as influence and cooks distance for data passed to the data argument. These measures are only defined for the original training data.

...

Additional arguments. Not used. Needed to match generic signature only. Cautionary note: Misspelled arguments will be absorbed in ..., where they will be ignored. If the misspelled argument has a default value, the default value will be used. For example, if you pass conf.lvel = 0.9, all computation will proceed using conf.level = 0.95. Additionally, if you pass newdata = my_tibble to an augment() method that does not accept a newdata argument, it will use the default value for the data argument.

Value

A tibble::tibble() with one row for each original observation with addition columns:

.fitted_j_0

population-level fitted values for the j-th longitudinal process

.fitted_j_1

individuals-level fitted values for the j-th longitudinal process

.resid_j_0

population-level residuals for the j-th longitudinal process

.resid_j_1

individual-level residuals for the j-th longitudinal process

Details

See joineRML::fitted.mjoint() and joineRML::residuals.mjoint() for more information on the difference between population-level and individual-level fitted values and residuals.

If fitting a joint model with a single longitudinal process, make sure you are using a named list to define the formula for the fixed and random effects of the longitudinal submodel.

Examples

# NOT RUN {
# Fit a joint model with bivariate longitudinal outcomes
library(joineRML)
data(heart.valve)
hvd <- heart.valve[!is.na(heart.valve$log.grad) &
                       !is.na(heart.valve$log.lvmi) &
                       heart.valve$num <= 50, ]
fit <- mjoint(
    formLongFixed = list(
        "grad" = log.grad ~ time + sex + hs,
        "lvmi" = log.lvmi ~ time + sex
    ),
    formLongRandom = list(
        "grad" = ~ 1 | num,
        "lvmi" = ~ time | num
    ),
    formSurv = Surv(fuyrs, status) ~ age,
    data = hvd,
    inits = list("gamma" = c(0.11, 1.51, 0.80)),
    timeVar = "time"
)

# Extract the survival fixed effects
tidy(fit)

# Extract the longitudinal fixed effects
tidy(fit, component = "longitudinal")

# Extract the survival fixed effects with confidence intervals
tidy(fit, ci = TRUE)

# Extract the survival fixed effects with confidence intervals based
# on bootstrapped standard errors
bSE <- bootSE(fit, nboot = 5, safe.boot = TRUE)
tidy(fit, boot_se = bSE, ci = TRUE)

# Augment original data with fitted longitudinal values and residuals
hvd2 <- augment(fit)

# Extract model statistics
glance(fit)
# }