inst/doc/article_html_varshrink.R

In VARshrink: Shrinkage Estimation Methods for Vector Autoregressive Models

## ----setup0, include = FALSE--------------------------------------------------
knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)

## ----echo = FALSE, warning=FALSE----------------------------------------------
text_tbl <- data.frame(
FM = c("VAR",                  "fevd",    "irf",              "predict", "summary",        "arch.test_sh", "normality.test_sh", "serial.test_sh", "stability_sh"), 
CL = c("varshrinkest, varest", "varfevd", "varshirf, varirf", "varprd",  "varshsum, varsum",    "varcheck",      "varcheck",          "varcheck",       "varstabil"),
MC = c("coef, fevd, fitted, irf, logLik, Phi, plot, predict, print, Psi, resid, summary",                              "plot, print", "plot, print",  "plot, print", "print",                "plot, print",   "plot, print",       "plot, print",    "plot, print"), 
FC = c("Acoef_sh, arch.test_sh, Bcoef_sh, BQ_sh, causality_sh, normality.test_sh, restrict_sh, roots_sh, serial.test_sh, stability_sh", " ", " ", "fanchart", " ", " ", " ", " ", " ")
)
colnames(text_tbl) <- c("Function or method", "Class", "Methods for class", "Functions for class")
kableExtra::column_spec(
  knitr::kable(text_tbl,
       caption = "Table 1. Structure of the package VARshrink."),
  1:4, width = "7em", border_left = FALSE, border_right = FALSE)

## ----setup, include = FALSE---------------------------------------------------
library(VARshrink)

## ----results = "hide", message=FALSE------------------------------------------
set.seed(1000)
myCoef <- list(A = list(matrix(c(0.5, 0, 0, 0.5), 2, 2)), c = c(0.2, 0.7))
myModel <- list(Coef = myCoef, Sigma = diag(0.1^2, 2), dof = Inf)
Y <- simVARmodel(numT = 100, model = myModel, burnin = 10)
resu_estim <- list()

## ----modeldemo, include = FALSE-----------------------------------------------
load("table2_modeldemo.RData")

## -----------------------------------------------------------------------------
resu_estim$`Ridge regression`

## -----------------------------------------------------------------------------
summary(resu_estim$`Ridge regression`)

## -----------------------------------------------------------------------------
resu_estim$`Nonparametric shrinkage`

## -----------------------------------------------------------------------------
summary(resu_estim$`Nonparametric shrinkage`)

## -----------------------------------------------------------------------------
resu_estim$`Full Bayes (fixed dof)`

## -----------------------------------------------------------------------------
summary(resu_estim$`Full Bayes (fixed dof)`)

## -----------------------------------------------------------------------------
resu_estim$`Full Bayes (estim dof)`

## -----------------------------------------------------------------------------
resu_estim$`Semi Bayes (fixed dof)`
summary(resu_estim$`Semi Bayes (fixed dof)`)

## -----------------------------------------------------------------------------
resu_estim$`Semi Bayes (estim dof)`

## -----------------------------------------------------------------------------
resu_estim$`K-fold CV (fixed dof)`

## ----eval = FALSE-------------------------------------------------------------
# resu_estim$`K-fold CV (estim dof)` <-
#   VARshrink(Y, p = 1, type = "const", method = "kcv", dof = NULL,
#             lambda = NULL, lambda_var = NULL, prior_type = "NCJ",
#             num_folds = 5, m0 = ncol(Y))

## -----------------------------------------------------------------------------
resu_sse <- data.frame(SSE = sapply(resu_estim,
  function(x) calcSSE_Acoef(Acoef_sh(x), myCoef$A)))

## ----echo = FALSE-------------------------------------------------------------
knitr::kable(round(resu_sse, 3),
             caption = "Table 2. Sum of squared errors of VAR coefficients estimated by the shrinkage methods.")

## ----diffCanada, out.width='70%', fig.cap = "Figure 1. The benchmark data set obtained by differencing the Canada data."----
data(Canada, package = "vars")
Y = diff(Canada)
plot(Y, cex.lab = 1.3)

## ----eval = FALSE-------------------------------------------------------------
# set.seed(1000)
# resu_model <- array(NA, dim = c(5, 2, 3),
#   dimnames = list(c("Ridge regression", "Nonparametric shrinkage",
#                     "Full Bayes", "Semi Bayes", "K-fold CV"),
#                   c("AIC", "BIC"), c("p=1", "p=2", "p=3")))
# for (p in 1:3) {
#   EstimRidge <- VARshrink(Y, p = p, type = "const", method = "ridge")
#   resu_model["Ridge regression", , p] <- c(AIC(EstimRidge), BIC(EstimRidge))
# 
#   EstimNS <- VARshrink(Y, p = p, type = "none", method = "ns")
#   resu_model["Nonparametric shrinkage", , p] <-
#     c(AIC(EstimNS), BIC(EstimNS))
# 
#   EstimFB <- VARshrink(Y, p = p, type = "const", method = "fbayes", dof = NULL)
#   resu_model["Full Bayes", , p] <- c(AIC(EstimFB), BIC(EstimFB))
# 
#   EstimSB <- VARshrink(Y, p = p, type = "const", method = "sbayes",
#                        dof = NULL, prior_type = "NCJ")
#   resu_model["Semi Bayes", , p] <- c(AIC(EstimSB), BIC(EstimSB))
# 
#   EstimKCV <- VARshrink(Y, p = p, type = "const", method = "kcv",
#                           dof = NULL, prior_type = "NCJ")
#   resu_model["K-fold CV", , p] <- c(AIC(EstimKCV), BIC(EstimKCV))
# }

## ----include = FALSE----------------------------------------------------------
load("table3_modelcomp.RData")

## ----modelcomp, echo = FALSE--------------------------------------------------
knitr::kable(round(resu_model, 1),
             caption = "Table 3. Information criteria (AIC, BIC) for model comparison.")

## ----pred, fig.cap="Figure 2. A 10-step ahead Forecasting of time series by the VAR model estimated by the nonparametric shrinkage method. The differenced Canada data were modeled by a VAR(2) model selected at the minimum BIC."----
plot(predict(VARshrink(Y, p = 2, type = "none", method = "ns")), names = "U")