library(fdid)
data(fdid) # loads `mortality`
# Unique unit ID and binary treatment factor
mortality$uniqueid <- paste(mortality$provid, mortality$countyid, sep = "-")
mortality$G <- as.integer(mortality$pczupu >= median(mortality$pczupu, na.rm = TRUE))
# Prepare wide-format data
s <- fdid_prepare(
data = mortality,
Y_label = "mortality",
X_labels = c("avggrain", "nograin", "urban", "dis_bj",
"dis_pc", "rice", "minority", "edu", "lnpop"),
G_label = "G",
unit_label = "uniqueid",
time_label = "year"
)
# Estimate
result <- fdid(s, tr_period = 1958:1961, ref_period = 1957)
summary(result)
#>
#> Factorial Difference-in-Differences (FDID) Summary
#> ════════════════════════════════════════════════════════════════════════
#> Method: ols1
#> Variance Type: robust
#> Reference Period: 1957
#> Pre-Event Period: 1954, 1955, 1956, 1957
#> Event Period: 1958, 1959, 1960, 1961
#> Post-Event Period: 1962, 1963, 1964, 1965, 1966
#> ════════════════════════════════════════════════════════════════════════
#>
#> Aggregate Estimates
#> ────────────────────────────────────────────────────────────────────────
#> Estimate Std.Error 95% CI
#> ────────────────────────────────────────────────────────────────────────
#> Pre-Event 0.3334 0.2103 [-0.0793, 0.7462]
#> Event -2.8024 0.7511 [-4.2766, -1.3283]
#> Post-Event -0.4893 0.2025 [-0.8866, -0.0920]
#> ────────────────────────────────────────────────────────────────────────
#>
#> Dynamic Estimates
#> ────────────────────────────────────────────────────────────────────────
#> Estimate Std.Error 95% CI
#> ────────────────────────────────────────────────────────────────────────
#> 1954 0.9565 0.2716 [0.4235, 1.4896]
#> 1955 0.2512 0.2663 [-0.2715, 0.7740]
#> 1956 -0.2074 0.2697 [-0.7367, 0.3218]
#> 1957 0.0000 0.0000 [0.0000, 0.0000]
#> ····································································
#> 1958 -0.8928 0.3800 [-1.6386, -0.1470]
#> 1959 -3.5169 1.1051 [-5.6857, -1.3481]
#> 1960 -5.6338 1.6781 [-8.9271, -2.3404]
#> 1961 -1.1662 0.7263 [-2.5915, 0.2592]
#> ····································································
#> 1962 -0.1948 0.3285 [-0.8395, 0.4499]
#> 1963 -0.5807 0.2601 [-1.0911, -0.0703]
#> 1964 -0.7401 0.2537 [-1.2380, -0.2421]
#> 1965 -0.4843 0.2185 [-0.9131, -0.0555]
#> 1966 -0.4466 0.2183 [-0.8751, -0.0180]
#> ────────────────────────────────────────────────────────────────────────
