plot_trends {tidysynth}

plot_trends

Description

Plot the observed and synthetic trends for the treated units.

Usage

plot_trends(data, time_window = NULL)

Arguments

data

nested data of type tbl_df.

time_window

time window of the trend plot.

Details

Synthetic control is a visual-based method, like Regression Discontinuity, so inspection of the pre-intervention period fits is key assessing the sythetic control's fit. A poor fit in the pre-period reduces confidence in the post-period trend capturing the counterfactual.

See ?generate_control() for information on how to generate a synthetic control unit.

Value

ggplot object of the observed and synthetic trends.

Examples

# Smoking example data
data(smoking)

smoking_out <-
smoking %>%

# initial the synthetic control object
synthetic_control(outcome = cigsale,
                  unit = state,
                  time = year,
                  i_unit = "California",
                  i_time = 1988,
                  generate_placebos=TRUE) %>%

# Generate the aggregate predictors used to generate the weights
  generate_predictor(time_window=1980:1988,
                     lnincome = mean(lnincome, na.rm = TRUE),
                     retprice = mean(retprice, na.rm = TRUE),
                     age15to24 = mean(age15to24, na.rm = TRUE)) %>%

  generate_predictor(time_window=1984:1988,
                     beer = mean(beer, na.rm = TRUE)) %>%

  generate_predictor(time_window=1975,
                     cigsale_1975 = cigsale) %>%

  generate_predictor(time_window=1980,
                     cigsale_1980 = cigsale) %>%

  generate_predictor(time_window=1988,
                     cigsale_1988 = cigsale) %>%


  # Generate the fitted weights for the synthetic control
  generate_weights(optimization_window =1970:1988,
                   Margin.ipop=.02,Sigf.ipop=7,Bound.ipop=6) %>%

  # Generate the synthetic control
  generate_control()

# Plot the observed and synthetic trend
smoking_out %>% plot_trends(time_window = 1970:2000)