Augment data with information from a(n) fixest object

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 at least all predictor variable columns used to fit the model are present. If the original outcome variable used to fit the model is not included in newdata, then no .resid column will be included in the output.

Augment will often behave differently depending on whether data or newdata is given. 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 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. If a predictor enters the model as part of a matrix of covariates, such as when the model formula uses splines::ns(), stats::poly(), or survival::Surv(), it is represented as a matrix column.

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.

Usage

# S3 method for class 'fixest'
augment(
  x,
  data = NULL,
  newdata = NULL,
  type.predict = c("link", "response"),
  type.residuals = c("response", "deviance", "pearson", "working"),
  ...
)

Arguments

x: A fixest object returned from any of the fixest estimators
data: A base::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.
newdata: A base::data.frame() or tibble::tibble() containing all the original predictors used to create x. Defaults to NULL, indicating that nothing has been passed to newdata. If newdata is specified, the data argument will be ignored.
type.predict: Passed to predict.fixest type argument. Defaults to "link" (like predict.glm).
type.residuals: Passed to predict.fixest type argument. Defaults to "response" (like residuals.lm, but unlike residuals.glm).
...: Additional arguments passed to summary and confint. Important arguments are se and cluster. Other arguments are dof, exact_dof, forceCovariance, and keepBounded. See summary.fixest.

Note

Important note: fixest models do not include a copy of the input data, so you must provide it manually.

augment.fixest only works for fixest::feols(), fixest::feglm(), and fixest::femlm() models. It does not work with results from fixest::fenegbin(), fixest::feNmlm(), or fixest::fepois().

Value

A tibble::tibble() with columns:

.fitted: Fitted or predicted value.
.resid: The difference between observed and fitted values.

Examples


# load libraries for models and data
library(fixest)
#> 
#> Attaching package: ‘fixest’
#> The following object is masked from ‘package:lfe’:
#> 
#>     fepois

gravity <-
  feols(
    log(Euros) ~ log(dist_km) | Origin + Destination + Product + Year, trade
  )

tidy(gravity)
#> # A tibble: 1 × 5
#>   term         estimate std.error statistic       p.value
#>   <chr>           <dbl>     <dbl>     <dbl>         <dbl>
#> 1 log(dist_km)    -2.17     0.154     -14.1 0.00000000119
glance(gravity)
#> # A tibble: 1 × 9
#>   r.squared adj.r.squared within.r.squared pseudo.r.squared sigma  nobs
#>       <dbl>         <dbl>            <dbl>            <dbl> <dbl> <int>
#> 1     0.706         0.705            0.219               NA  1.74 38325
#> # ℹ 3 more variables: AIC <dbl>, BIC <dbl>, logLik <dbl>
augment(gravity, trade)
#> # A tibble: 38,325 × 9
#>    .rownames Destination Origin Product  Year dist_km    Euros .fitted
#>    <chr>     <fct>       <fct>    <int> <dbl>   <dbl>    <dbl>   <dbl>
#>  1 1         LU          BE           1  2007    140.  2966697    14.1
#>  2 2         BE          LU           1  2007    140.  6755030    13.0
#>  3 3         LU          BE           2  2007    140. 57078782    16.9
#>  4 4         BE          LU           2  2007    140.  7117406    15.8
#>  5 5         LU          BE           3  2007    140. 17379821    16.3
#>  6 6         BE          LU           3  2007    140.  2622254    15.2
#>  7 7         LU          BE           4  2007    140. 64867588    17.4
#>  8 8         BE          LU           4  2007    140. 10731757    16.3
#>  9 9         LU          BE           5  2007    140.   330702    14.1
#> 10 10        BE          LU           5  2007    140.     7706    13.0
#> # ℹ 38,315 more rows
#> # ℹ 1 more variable: .resid <dbl>

# to get robust or clustered SEs, users can either:

# 1) specify the arguments directly in the `tidy()` call

tidy(gravity, conf.int = TRUE, cluster = c("Product", "Year"))
#> # A tibble: 1 × 7
#>   term         estimate std.error statistic  p.value conf.low conf.high
#>   <chr>           <dbl>     <dbl>     <dbl>    <dbl>    <dbl>     <dbl>
#> 1 log(dist_km)    -2.17    0.0760     -28.5 3.88e-10    -2.34     -2.00

tidy(gravity, conf.int = TRUE, se = "threeway")
#> # A tibble: 1 × 7
#>   term         estimate std.error statistic     p.value conf.low conf.high
#>   <chr>           <dbl>     <dbl>     <dbl>       <dbl>    <dbl>     <dbl>
#> 1 log(dist_km)    -2.17     0.175     -12.4     6.08e-9    -2.54     -1.79

# 2) or, feed tidy() a summary.fixest object that has already accepted
# these arguments

gravity_summ <- summary(gravity, cluster = c("Product", "Year"))

tidy(gravity_summ, conf.int = TRUE)
#> # A tibble: 1 × 7
#>   term         estimate std.error statistic  p.value conf.low conf.high
#>   <chr>           <dbl>     <dbl>     <dbl>    <dbl>    <dbl>     <dbl>
#> 1 log(dist_km)    -2.17    0.0760     -28.5 3.88e-10    -2.34     -2.00

# approach (1) is preferred.