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Compare event studies on one plot

Source: R/plot-did.R
eventplot.Rd

Draws the event-time effects of several fits on one axis, offset horizontally, with pointwise confidence intervals and a legend: for example the two-way fixed-effects event study of eventstudy(), the Callaway and Sant'Anna estimator of attgt() and the extended two-way fixed-effects estimator of etwfe(). Uniform bands are not drawn here; use the plot() method of a single fit for them.

Usage

eventplot(
  ...,
  labels = NULL,
  min_e = -Inf,
  max_e = Inf,
  col = c("black", "#D55E00", "#0072B2", "#009E73", "#CC79A7"),
  pch = c(19, 17, 15, 18, 25),
  offset = 0.2,
  legend = TRUE,
  xlab = "Event time",
  ylab = "Estimate",
  main = NULL,
  ylim = NULL,
  style = c("classic", "points", "line"),
  ref = NULL,
  onset = NULL,
  onset_label = NA,
  caps = NULL
)

Arguments

...

fits from eventstudy(), attgt() or etwfe() (or the event-time summaries of the last two). Names of the arguments are used as labels.

labels

optional labels, one per fit (default: the argument names, else the estimator)

min_e, max_e

event window to plot

col, pch

colours and (filled) plotting symbols, recycled over the fits; the hollow version of each symbol is used before treatment

offset

horizontal distance between the fits, in event-time units

legend

logical: add a legend

xlab, ylab, main, ylim

axis labels, title and y-axis limits

style

"classic" (default), "points" or "line" (see Styles); for the event-time, cohort and calendar plots

ref

event time of the reference period, marked when the estimate of a fit is exactly zero there; the default (NULL) uses the omitted period of each fit (-1, or the ref of an eventstudy() fit)

onset

position of the dashed treatment-onset line on the event time axis: NULL gives 0 for style = "classic" and -0.5 (between the last pre-treatment and the first treated period) otherwise

onset_label

text written above the onset line; the default (NA) is "Intervention" for style = "classic" and none otherwise, NULL suppresses it

caps

logical: draw caps on the confidence-interval whiskers; the default (NULL) draws them for style = "classic" only

Value

a data frame of the plotted estimates (model, event, estimate, lower, upper), invisibly

Details

The styles are those of plot.panglm_attgt(). With style = "classic" (the default) the points are filled, the whiskers capped, each reference period is a hollow symbol at zero and the dashed onset line is at event time 0, labelled "Intervention". With style = "points" the points are hollow before treatment and filled after, and the onset line is at -0.5. With style = "line" each fit is a coloured line with its pointwise intervals as a semi-transparent band (the fits are not offset).

See also

Other policy evaluation: attgt(), did(), etwfe(), eventstudy(), panelplot(), treatmentplot(), trendplot()

Examples

set.seed(2)
d <- expand.grid(id = 1:150, t = 1:8)
d$first <- rep(c(4, 6, NA), each = 50)[d$id]
d$y <- rnorm(150)[d$id] + 0.2 * d$t +
  ifelse(!is.na(d$first) & d$t >= d$first, 1, 0) + rnorm(nrow(d))
es <- eventstudy(y ~ 1, d, index = c("id", "t"), treat = "first",
                 leads = 3, lags = 3)
cs <- attgt(y ~ 1, d, index = c("id", "t"), treat = "first")
ew <- etwfe(y ~ 1, d, index = c("id", "t"), treat = "first", control = "never")
eventplot(TWFE = es, CS = cs, ETWFE = ew, min_e = -3, max_e = 3)

eventplot(TWFE = es, ETWFE = ew, min_e = -3, max_e = 3, style = "points")

eventplot(TWFE = es, CS = cs, min_e = -3, max_e = 3, style = "line")