\name{Greene2003}
\alias{Greene2003}

\title{Data and Examples from Greene (2003)}

\description{
This manual page collects a list of examples from the book. Some 
solutions might not be exact and the list is certainly not complete.
If you have suggestions for improvement (preferably in the form of code),
please contact the package maintainer.
}

\references{
Greene, W.H. (2003). \emph{Econometric Analysis}, 5th edition. Upper Saddle River, NJ: Prentice Hall.
URL \url{https://pages.stern.nyu.edu/~wgreene/Text/tables/tablelist5.htm}.
}

\seealso{\code{\link{Affairs}}, \code{\link{BondYield}}, \code{\link{CreditCard}},
  \code{\link{Electricity1955}}, \code{\link{Electricity1970}}, \code{\link{Equipment}},
  \code{\link{Grunfeld}}, \code{\link{KleinI}}, \code{\link{Longley}},
  \code{\link{ManufactCosts}}, \code{\link{MarkPound}}, \code{\link{Municipalities}},
  \code{\link{ProgramEffectiveness}}, \code{\link{PSID1976}}, \code{\link{SIC33}},
  \code{\link{ShipAccidents}}, \code{\link{StrikeDuration}}, \code{\link{TechChange}},
  \code{\link{TravelMode}}, \code{\link{UKInflation}}, \code{\link{USConsump1950}},
  \code{\link{USConsump1979}}, \code{\link{USGasG}}, \code{\link{USAirlines}},
  \code{\link{USInvest}}, \code{\link{USMacroG}}, \code{\link{USMoney}}}

\examples{
\dontshow{ if(!requireNamespace("dynlm") ||
              !requireNamespace("strucchange") ||
              !requireNamespace("MASS") ||
              !requireNamespace("plm") ||
              !requireNamespace("pscl") ||
              !requireNamespace("tseries") ||
              !requireNamespace("systemfit") ||
              !requireNamespace("sampleSelection")) {
  if(interactive() || is.na(Sys.getenv("_R_CHECK_PACKAGE_NAME_", NA))) {
    stop("not all packages required for the example are installed")
  } else q() }}
\donttest{
#####################################
## US consumption data (1970-1979) ##
#####################################

## Example 1.1
data("USConsump1979", package = "AER")
plot(expenditure ~ income, data = as.data.frame(USConsump1979), pch = 19)
fm <- lm(expenditure ~ income, data = as.data.frame(USConsump1979))
summary(fm)
abline(fm)


#####################################
## US consumption data (1940-1950) ##
#####################################

## data
data("USConsump1950", package = "AER")
usc <- as.data.frame(USConsump1950)
usc$war <- factor(usc$war, labels = c("no", "yes"))

## Example 2.1
plot(expenditure ~ income, data = usc, type = "n", xlim = c(225, 375), ylim = c(225, 350))
with(usc, text(income, expenditure, time(USConsump1950)))

## single model
fm <- lm(expenditure ~ income, data = usc)
summary(fm)

## different intercepts for war yes/no
fm2 <- lm(expenditure ~ income + war, data = usc)
summary(fm2)

## compare
anova(fm, fm2)

## visualize
abline(fm, lty = 3)                                   
abline(coef(fm2)[1:2])                                
abline(sum(coef(fm2)[c(1, 3)]), coef(fm2)[2], lty = 2)

## Example 3.2
summary(fm)$r.squared
summary(lm(expenditure ~ income, data = usc, subset = war == "no"))$r.squared
summary(fm2)$r.squared


########################
## US investment data ##
########################

data("USInvest", package = "AER")

## Chapter 3 in Greene (2003)
## transform (and round) data to match Table 3.1
us <- as.data.frame(USInvest)
us$invest <- round(0.1 * us$invest/us$price, digits = 3)
us$gnp <- round(0.1 * us$gnp/us$price, digits = 3)
us$inflation <- c(4.4, round(100 * diff(us$price)/us$price[-15], digits = 2))
us$trend <- 1:15
us <- us[, c(2, 6, 1, 4, 5)]

## p. 22-24
coef(lm(invest ~ trend + gnp, data = us))
coef(lm(invest ~ gnp, data = us))

## Example 3.1, Table 3.2
cor(us)[1,-1]
pcor <- solve(cor(us))
dcor <- 1/sqrt(diag(pcor))
pcor <- (-pcor * (dcor \%o\% dcor))[1,-1]

## Table 3.4
fm  <- lm(invest ~ trend + gnp + interest + inflation, data = us)
fm1 <- lm(invest ~ 1, data = us)
anova(fm1, fm)

## Example 4.1
set.seed(123)
w <- rnorm(10000)
x <- rnorm(10000)
eps <- 0.5 * w
y <- 0.5 + 0.5 * x + eps
b <- rep(0, 500)
for(i in 1:500) {
  ix <- sample(1:10000, 100)
  b[i] <- lm.fit(cbind(1, x[ix]), y[ix])$coef[2]
}
hist(b, breaks = 20, col = "lightgray")


###############################
## Longley's regression data ##
###############################

## package and data
data("Longley", package = "AER")
library("dynlm")

## Example 4.6
fm1 <- dynlm(employment ~ time(employment) + price + gnp + armedforces,
  data = Longley)
fm2 <- update(fm1, end = 1961)
cbind(coef(fm2), coef(fm1))

## Figure 4.3
plot(rstandard(fm2), type = "b", ylim = c(-3, 3))
abline(h = c(-2, 2), lty = 2)


#########################################
## US gasoline market data (1960-1995) ##
#########################################

## data
data("USGasG", package = "AER")

## Greene (2003)
## Example 2.3
fm <- lm(log(gas/population) ~ log(price) + log(income) + log(newcar) + log(usedcar),
  data = as.data.frame(USGasG))
summary(fm)

## Example 4.4
## estimates and standard errors (note different offset for intercept)
coef(fm)
sqrt(diag(vcov(fm)))
## confidence interval
confint(fm, parm = "log(income)")
## test linear hypothesis
linearHypothesis(fm, "log(income) = 1")

## Figure 7.5
plot(price ~ gas, data = as.data.frame(USGasG), pch = 19,
  col = (time(USGasG) > 1973) + 1)
legend("topleft", legend = c("after 1973", "up to 1973"), pch = 19, col = 2:1, bty = "n")

## Example 7.6
## re-used in Example 8.3
## linear time trend
ltrend <- 1:nrow(USGasG)
## shock factor
shock <- factor(time(USGasG) > 1973, levels = c(FALSE, TRUE), labels = c("before", "after"))

## 1960-1995
fm1 <- lm(log(gas/population) ~ log(income) + log(price) + log(newcar) + log(usedcar) + ltrend,
  data = as.data.frame(USGasG))
summary(fm1)
## pooled
fm2 <- lm(
  log(gas/population) ~ shock + log(income) + log(price) + log(newcar) + log(usedcar) + ltrend,
  data = as.data.frame(USGasG))
summary(fm2)
## segmented
fm3 <- lm(
  log(gas/population) ~ shock/(log(income) + log(price) + log(newcar) + log(usedcar) + ltrend),
  data = as.data.frame(USGasG))
summary(fm3)

## Chow test
anova(fm3, fm1)
library("strucchange")
sctest(log(gas/population) ~ log(income) + log(price) + log(newcar) + log(usedcar) + ltrend,
  data = USGasG, point = c(1973, 1), type = "Chow")
## Recursive CUSUM test
rcus <- efp(log(gas/population) ~ log(income) + log(price) + log(newcar) + log(usedcar) + ltrend,
   data = USGasG, type = "Rec-CUSUM")
plot(rcus)
sctest(rcus)
## Note: Greene's remark that the break is in 1984 (where the process crosses its boundary)
## is wrong. The break appears to be no later than 1976.

## Example 12.2
library("dynlm")
resplot <- function(obj, bound = TRUE) {
  res <- residuals(obj)
  sigma <- summary(obj)$sigma
  plot(res, ylab = "Residuals", xlab = "Year")
  grid()
  abline(h = 0)
  if(bound) abline(h = c(-2, 2) * sigma, col = "red")  
  lines(res)
}
resplot(dynlm(log(gas/population) ~ log(price), data = USGasG))
resplot(dynlm(log(gas/population) ~ log(price) + log(income), data = USGasG))
resplot(dynlm(log(gas/population) ~ log(price) + log(income) + log(newcar) + log(usedcar) +
  log(transport) + log(nondurable) + log(durable) +log(service) + ltrend, data = USGasG))
## different shock variable than in 7.6
shock <- factor(time(USGasG) > 1974, levels = c(FALSE, TRUE), labels = c("before", "after"))
resplot(dynlm(log(gas/population) ~ shock/(log(price) + log(income) + log(newcar) + log(usedcar) +
  log(transport) + log(nondurable) + log(durable) + log(service) + ltrend), data = USGasG))
## NOTE: something seems to be wrong with the sigma estimates in the `full' models

## Table 12.4, OLS
fm <- dynlm(log(gas/population) ~ log(price) + log(income) + log(newcar) + log(usedcar),
  data = USGasG)
summary(fm)
resplot(fm, bound = FALSE)
dwtest(fm)

## ML
g <- as.data.frame(USGasG)
y <- log(g$gas/g$population)
X <- as.matrix(cbind(log(g$price), log(g$income), log(g$newcar), log(g$usedcar)))
arima(y, order = c(1, 0, 0), xreg = X)


#######################################
## US macroeconomic data (1950-2000) ##
#######################################
## data and trend
data("USMacroG", package = "AER")
ltrend <- 0:(nrow(USMacroG) - 1)

## Example 5.3
## OLS and IV regression
library("dynlm")
fm_ols <- dynlm(consumption ~ gdp, data = USMacroG)
fm_iv <- dynlm(consumption ~ gdp | L(consumption) + L(gdp), data = USMacroG)

## Hausman statistic
library("MASS")
b_diff <- coef(fm_iv) - coef(fm_ols)
v_diff <- summary(fm_iv)$cov.unscaled - summary(fm_ols)$cov.unscaled
(t(b_diff) \%*\% ginv(v_diff) \%*\% b_diff) / summary(fm_ols)$sigma^2

## Wu statistic
auxreg <- dynlm(gdp ~ L(consumption) + L(gdp), data = USMacroG)
coeftest(dynlm(consumption ~ gdp + fitted(auxreg), data = USMacroG))[3,3] 
## agrees with Greene (but not with errata)

## Example 6.1
## Table 6.1
fm6.1 <- dynlm(log(invest) ~ tbill + inflation + log(gdp) + ltrend, data = USMacroG)
fm6.3 <- dynlm(log(invest) ~ I(tbill - inflation) + log(gdp) + ltrend, data = USMacroG)
summary(fm6.1)
summary(fm6.3)
deviance(fm6.1)
deviance(fm6.3)
vcov(fm6.1)[2,3] 

## F test
linearHypothesis(fm6.1, "tbill + inflation = 0")
## alternatively
anova(fm6.1, fm6.3)
## t statistic
sqrt(anova(fm6.1, fm6.3)[2,5])
 
## Example 6.3
## Distributed lag model:
## log(Ct) = b0 + b1 * log(Yt) + b2 * log(C(t-1)) + u
us <- log(USMacroG[, c(2, 5)])
fm_distlag <- dynlm(log(consumption) ~ log(dpi) + L(log(consumption)),
  data = USMacroG)
summary(fm_distlag)

## estimate and test long-run MPC 
coef(fm_distlag)[2]/(1-coef(fm_distlag)[3])
linearHypothesis(fm_distlag, "log(dpi) + L(log(consumption)) = 1")
## correct, see errata
 
## Example 6.4
## predict investiment in 2001(1)
predict(fm6.1, interval = "prediction",
  newdata = data.frame(tbill = 4.48, inflation = 5.262, gdp = 9316.8, ltrend = 204))

## Example 7.7
## no GMM available in "strucchange"
## using OLS instead yields
fs <- Fstats(log(m1/cpi) ~ log(gdp) + tbill, data = USMacroG,
  vcov = NeweyWest, from = c(1957, 3), to = c(1991, 3))
plot(fs)
## which looks somewhat similar ...
 
## Example 8.2
## Ct = b0 + b1*Yt + b2*Y(t-1) + v
fm1 <- dynlm(consumption ~ dpi + L(dpi), data = USMacroG)
## Ct = a0 + a1*Yt + a2*C(t-1) + u
fm2 <- dynlm(consumption ~ dpi + L(consumption), data = USMacroG)

## Cox test in both directions:
coxtest(fm1, fm2)
## ... and do the same for jtest() and encomptest().
## Notice that in this particular case two of them are coincident.
jtest(fm1, fm2)
encomptest(fm1, fm2)
## encomptest could also be performed `by hand' via
fmE <- dynlm(consumption ~ dpi + L(dpi) + L(consumption), data = USMacroG)
waldtest(fm1, fmE, fm2)

## Table 9.1
fm_ols <- lm(consumption ~ dpi, data = as.data.frame(USMacroG))
fm_nls <- nls(consumption ~ alpha + beta * dpi^gamma,
  start = list(alpha = coef(fm_ols)[1], beta = coef(fm_ols)[2], gamma = 1),
  control = nls.control(maxiter = 100), data = as.data.frame(USMacroG))
summary(fm_ols)
summary(fm_nls)
deviance(fm_ols)
deviance(fm_nls)
vcov(fm_nls)

## Example 9.7
## F test
fm_nls2 <- nls(consumption ~ alpha + beta * dpi,
  start = list(alpha = coef(fm_ols)[1], beta = coef(fm_ols)[2]),
  control = nls.control(maxiter = 100), data = as.data.frame(USMacroG))
anova(fm_nls, fm_nls2)
## Wald test
linearHypothesis(fm_nls, "gamma = 1")

## Example 9.8, Table 9.2
usm <- USMacroG[, c("m1", "tbill", "gdp")]
fm_lin <- lm(m1 ~ tbill + gdp, data = usm)
fm_log <- lm(m1 ~ tbill + gdp, data = log(usm))
## PE auxiliary regressions
aux_lin <- lm(m1 ~ tbill + gdp + I(fitted(fm_log) - log(fitted(fm_lin))), data = usm)
aux_log <- lm(m1 ~ tbill + gdp + I(fitted(fm_lin) - exp(fitted(fm_log))), data = log(usm))
coeftest(aux_lin)[4,]
coeftest(aux_log)[4,]
## matches results from errata
## With lmtest >= 0.9-24:
## petest(fm_lin, fm_log)

## Example 12.1
fm_m1 <- dynlm(log(m1) ~ log(gdp) + log(cpi), data = USMacroG)
summary(fm_m1)

## Figure 12.1
par(las = 1)
plot(0, 0, type = "n", axes = FALSE,
     xlim = c(1950, 2002), ylim = c(-0.3, 0.225),
     xaxs = "i", yaxs = "i",
     xlab = "Quarter", ylab = "", main = "Least Squares Residuals")
box()
axis(1, at = c(1950, 1963, 1976, 1989, 2002))
axis(2, seq(-0.3, 0.225, by = 0.075))
grid(4, 7, col = grey(0.6))
abline(0, 0)
lines(residuals(fm_m1), lwd = 2)

## Example 12.3
fm_pc <- dynlm(d(inflation) ~ unemp, data = USMacroG)
summary(fm_pc)
## Figure 12.3
plot(residuals(fm_pc))
## natural unemployment rate
coef(fm_pc)[1]/coef(fm_pc)[2]
## autocorrelation
res <- residuals(fm_pc)
summary(dynlm(res ~ L(res)))

## Example 12.4
coeftest(fm_m1)
coeftest(fm_m1, vcov = NeweyWest(fm_m1, lag = 5))
summary(fm_m1)$r.squared
dwtest(fm_m1)
as.vector(acf(residuals(fm_m1), plot = FALSE)$acf)[2]
## matches Tab. 12.1 errata and Greene 6e, apart from Newey-West SE


#################################################
## Cost function of electricity producers 1870 ##
#################################################

## Example 5.6: a generalized Cobb-Douglas cost function
data("Electricity1970", package = "AER")
fm <- lm(log(cost/fuel) ~ log(output) + I(log(output)^2/2) + 
  log(capital/fuel) + log(labor/fuel), data=Electricity1970[1:123,])


####################################################
## SIC 33: Production for primary metals industry ##
####################################################

## data
data("SIC33", package = "AER")

## Example 6.2
## Translog model
fm_tl <- lm(
  output ~ labor + capital + I(0.5 * labor^2) + I(0.5 * capital^2) + I(labor * capital),
  data = log(SIC33))
## Cobb-Douglas model
fm_cb <- lm(output ~ labor + capital, data = log(SIC33))

## Table 6.2 in Greene (2003)
deviance(fm_tl)
deviance(fm_cb)
summary(fm_tl)
summary(fm_cb)
vcov(fm_tl)
vcov(fm_cb)

## Cobb-Douglas vs. Translog model
anova(fm_cb, fm_tl)
## hypothesis of constant returns
linearHypothesis(fm_cb, "labor + capital = 1")


###############################
## Cost data for US airlines ##
###############################

## data
data("USAirlines", package = "AER")

## Example 7.2
fm_full <- lm(log(cost) ~ log(output) + I(log(output)^2) + log(price) + load + year + firm,
  data = USAirlines)
fm_time <- lm(log(cost) ~ log(output) + I(log(output)^2) + log(price) + load + year,
  data = USAirlines)
fm_firm <- lm(log(cost) ~ log(output) + I(log(output)^2) + log(price) + load + firm,
  data = USAirlines)
fm_no <- lm(log(cost) ~ log(output) + I(log(output)^2) + log(price) + load, data = USAirlines)

## full fitted model
coef(fm_full)[1:5]
plot(1970:1984, c(coef(fm_full)[6:19], 0), type = "n",
     xlab = "Year", ylab = expression(delta(Year)),
     main = "Estimated Year Specific Effects")
grid()
points(1970:1984, c(coef(fm_full)[6:19], 0), pch = 19)

## Table 7.2
anova(fm_full, fm_time)
anova(fm_full, fm_firm)
anova(fm_full, fm_no)

## alternatively, use plm()
library("plm")
usair <- pdata.frame(USAirlines, c("firm", "year"))
fm_full2 <- plm(log(cost) ~ log(output) + I(log(output)^2) + log(price) + load,
  data = usair, model = "within", effect = "twoways")
fm_time2 <- plm(log(cost) ~ log(output) + I(log(output)^2) + log(price) + load,
  data = usair, model = "within", effect = "time")
fm_firm2 <- plm(log(cost) ~ log(output) + I(log(output)^2) + log(price) + load,
  data = usair, model = "within", effect = "individual")
fm_no2 <- plm(log(cost) ~ log(output) + I(log(output)^2) + log(price) + load,
  data = usair, model = "pooling")
pFtest(fm_full2, fm_time2)
pFtest(fm_full2, fm_firm2)
pFtest(fm_full2, fm_no2)


## Example 13.1, Table 13.1
fm_no <- plm(log(cost) ~ log(output) + log(price) + load, data = usair, model = "pooling")
fm_gm <- plm(log(cost) ~ log(output) + log(price) + load, data = usair, model = "between")
fm_firm <- plm(log(cost) ~ log(output) + log(price) + load, data = usair, model = "within")
fm_time <- plm(log(cost) ~ log(output) + log(price) + load, data = usair, model = "within",
  effect = "time")
fm_ft <- plm(log(cost) ~ log(output) + log(price) + load, data = usair, model = "within",
  effect = "twoways")

summary(fm_no)
summary(fm_gm)
summary(fm_firm)
fixef(fm_firm)
summary(fm_time)
fixef(fm_time)
summary(fm_ft)
fixef(fm_ft, effect = "individual")
fixef(fm_ft, effect = "time")

## Table 13.2
fm_rfirm <- plm(log(cost) ~ log(output) + log(price) + load, data = usair, model = "random")
fm_rft <- plm(log(cost) ~ log(output) + log(price) + load, data = usair, model = "random",
  effect = "twoways")
summary(fm_rfirm)
summary(fm_rft)


#################################################
## Cost function of electricity producers 1955 ##
#################################################

## Nerlove data
data("Electricity1955", package = "AER")
Electricity <- Electricity1955[1:145,]

## Example 7.3
## Cobb-Douglas cost function
fm_all <- lm(log(cost/fuel) ~ log(output) + log(labor/fuel) + log(capital/fuel),
  data = Electricity)
summary(fm_all)

## hypothesis of constant returns to scale
linearHypothesis(fm_all, "log(output) = 1")

## Figure 7.4
plot(residuals(fm_all) ~ log(output), data = Electricity)
## scaling seems to be different in Greene (2003) with logQ > 10?

## grouped functions
Electricity$group <- with(Electricity, cut(log(output), quantile(log(output), 0:5/5),
  include.lowest = TRUE, labels = 1:5))
fm_group <- lm(
  log(cost/fuel) ~ group/(log(output) + log(labor/fuel) + log(capital/fuel)) - 1,
  data = Electricity)

## Table 7.3 (close, but not quite)
round(rbind(coef(fm_all)[-1], matrix(coef(fm_group), nrow = 5)[,-1]), digits = 3)

## Table 7.4
## log quadratic cost function
fm_all2 <- lm(
  log(cost/fuel) ~ log(output) + I(log(output)^2) + log(labor/fuel) + log(capital/fuel),
  data = Electricity)
summary(fm_all2)


##########################
## Technological change ##
##########################

## Exercise 7.1
data("TechChange", package = "AER")
fm1 <- lm(I(output/technology) ~ log(clr), data = TechChange)
fm2 <- lm(I(output/technology) ~ I(1/clr), data = TechChange)
fm3 <- lm(log(output/technology) ~ log(clr), data = TechChange)
fm4 <- lm(log(output/technology) ~ I(1/clr), data = TechChange)

## Exercise 7.2 (a) and (c)
plot(I(output/technology) ~ clr, data = TechChange)
sctest(I(output/technology) ~ log(clr), data = TechChange,
  type = "Chow", point = c(1942, 1))


##################################
## Expenditure and default data ##
##################################

## full data set (F21.4)
data("CreditCard", package = "AER")

## extract data set F9.1
ccard <- CreditCard[1:100,]
ccard$income <- round(ccard$income, digits = 2)
ccard$expenditure <- round(ccard$expenditure, digits = 2)
ccard$age <- round(ccard$age + .01)
## suspicious:
CreditCard$age[CreditCard$age < 1]
## the first of these is also in TableF9.1 with 36 instead of 0.5:
ccard$age[79] <- 36

## Example 11.1
ccard <- ccard[order(ccard$income),]
ccard0 <- subset(ccard, expenditure > 0)
cc_ols <- lm(expenditure ~ age + owner + income + I(income^2), data = ccard0)

## Figure 11.1
plot(residuals(cc_ols) ~ income, data = ccard0, pch = 19)

## Table 11.1
mean(ccard$age)
prop.table(table(ccard$owner))
mean(ccard$income)

summary(cc_ols)
sqrt(diag(vcovHC(cc_ols, type = "HC0")))
sqrt(diag(vcovHC(cc_ols, type = "HC2"))) 
sqrt(diag(vcovHC(cc_ols, type = "HC1")))

bptest(cc_ols, ~ (age + income + I(income^2) + owner)^2 + I(age^2) + I(income^4),
  data = ccard0)
gqtest(cc_ols)
bptest(cc_ols, ~ income + I(income^2), data = ccard0, studentize = FALSE)
bptest(cc_ols, ~ income + I(income^2), data = ccard0)

## Table 11.2, WLS and FGLS
cc_wls1 <- lm(expenditure ~ age + owner + income + I(income^2), weights = 1/income,
  data = ccard0)
cc_wls2 <- lm(expenditure ~ age + owner + income + I(income^2), weights = 1/income^2,
  data = ccard0)

auxreg1 <- lm(log(residuals(cc_ols)^2) ~ log(income), data = ccard0)
cc_fgls1 <- lm(expenditure ~ age + owner + income + I(income^2),
  weights = 1/exp(fitted(auxreg1)), data = ccard0)

auxreg2 <- lm(log(residuals(cc_ols)^2) ~ income + I(income^2), data = ccard0)
cc_fgls2 <- lm(expenditure ~ age + owner + income + I(income^2),
  weights = 1/exp(fitted(auxreg2)), data = ccard0)

alphai <- coef(lm(log(residuals(cc_ols)^2) ~ log(income), data = ccard0))[2]
alpha <- 0
while(abs((alphai - alpha)/alpha) > 1e-7) {
  alpha <- alphai
  cc_fgls3 <- lm(expenditure ~ age + owner + income + I(income^2), weights = 1/income^alpha,
    data = ccard0)
  alphai <- coef(lm(log(residuals(cc_fgls3)^2) ~ log(income), data = ccard0))[2]
}
alpha ## 1.7623 for Greene
cc_fgls3 <- lm(expenditure ~ age + owner + income + I(income^2), weights = 1/income^alpha,
  data = ccard0)

llik <- function(alpha)
  -logLik(lm(expenditure ~ age + owner + income + I(income^2), weights = 1/income^alpha,
    data = ccard0))
plot(0:100/20, -sapply(0:100/20, llik), type = "l", xlab = "alpha", ylab = "logLik")
alpha <- optimize(llik, interval = c(0, 5))$minimum
cc_fgls4 <- lm(expenditure ~ age + owner + income + I(income^2), weights = 1/income^alpha,
  data = ccard0)

## Table 11.2
cc_fit <- list(cc_ols, cc_wls1, cc_wls2, cc_fgls2, cc_fgls1, cc_fgls3, cc_fgls4)
t(sapply(cc_fit, coef))
t(sapply(cc_fit, function(obj) sqrt(diag(vcov(obj)))))

## Table 21.21, Poisson and logit models
cc_pois <- glm(reports ~ age + income + expenditure, data = CreditCard, family = poisson)
summary(cc_pois)
logLik(cc_pois)
xhat <- colMeans(CreditCard[, c("age", "income", "expenditure")])
xhat <- as.data.frame(t(xhat))
lambda <- predict(cc_pois, newdata = xhat, type = "response")
ppois(0, lambda) * nrow(CreditCard)

cc_logit <- glm(factor(reports > 0) ~ age + income + owner,
  data = CreditCard, family = binomial)
summary(cc_logit)
logLik(cc_logit)

## Table 21.21, "split population model"
library("pscl")
cc_zip <- zeroinfl(reports ~ age + income + expenditure | age + income + owner,
  data = CreditCard)
summary(cc_zip)
sum(predict(cc_zip, type = "prob")[,1])


###################################
## DEM/GBP exchange rate returns ##
###################################

## data as given by Greene (2003)
data("MarkPound")
mp <- round(MarkPound, digits = 6)

## Figure 11.3 in Greene (2003)
plot(mp)

## Example 11.8 in Greene (2003), Table 11.5
library("tseries")
mp_garch <- garch(mp, grad = "numerical")
summary(mp_garch)
logLik(mp_garch)  
## Greene (2003) also includes a constant and uses different
## standard errors (presumably computed from Hessian), here
## OPG standard errors are used. garchFit() in "fGarch"
## implements the approach used by Greene (2003).

## compare Errata to Greene (2003)
library("dynlm")
res <- residuals(dynlm(mp ~ 1))^2
mp_ols <- dynlm(res ~ L(res, 1:10))
summary(mp_ols)
logLik(mp_ols)
summary(mp_ols)$r.squared * length(residuals(mp_ols))


################################
## Grunfeld's investment data ##
################################

## subset of data with mistakes
data("Grunfeld", package = "AER")
ggr <- subset(Grunfeld, firm \%in\% c("General Motors", "US Steel",
  "General Electric", "Chrysler", "Westinghouse"))
ggr[c(26, 38), 1] <- c(261.6, 645.2)
ggr[32, 3] <- 232.6

## Tab. 13.4
fm_pool <- lm(invest ~ value + capital, data = ggr)
summary(fm_pool)
logLik(fm_pool)
## White correction
sqrt(diag(vcovHC(fm_pool, type = "HC0")))

## heteroskedastic FGLS
auxreg1 <- lm(residuals(fm_pool)^2 ~ firm - 1, data = ggr)
fm_pfgls <- lm(invest ~ value + capital, data = ggr, weights = 1/fitted(auxreg1))
summary(fm_pfgls)

## ML, computed as iterated FGLS
sigmasi <- fitted(lm(residuals(fm_pfgls)^2 ~ firm - 1 , data = ggr))
sigmas <- 0
while(any(abs((sigmasi - sigmas)/sigmas) > 1e-7)) {
   sigmas <- sigmasi
   fm_pfgls_i <- lm(invest ~ value + capital, data = ggr, weights = 1/sigmas)
   sigmasi <- fitted(lm(residuals(fm_pfgls_i)^2 ~ firm - 1 , data = ggr))
   }
fm_pmlh <- lm(invest ~ value + capital, data = ggr, weights = 1/sigmas)
summary(fm_pmlh)
logLik(fm_pmlh)

## Tab. 13.5
auxreg2 <- lm(residuals(fm_pfgls)^2 ~ firm - 1, data = ggr)
auxreg3 <- lm(residuals(fm_pmlh)^2 ~ firm - 1, data = ggr)
rbind(
  "OLS" = coef(auxreg1),
  "Het. FGLS" = coef(auxreg2),
  "Het. ML" = coef(auxreg3))


## Chapter 14: explicitly treat as panel data
library("plm")
pggr <- pdata.frame(ggr, c("firm", "year"))

## Tab. 14.1
library("systemfit")
fm_sur <- systemfit(invest ~ value + capital, data = pggr, method = "SUR",
  methodResidCov = "noDfCor")
fm_psur <- systemfit(invest ~ value + capital, data = pggr, method = "SUR", pooled = TRUE, 
  methodResidCov = "noDfCor", residCovWeighted = TRUE)

## Tab 14.2
fm_ols <- systemfit(invest ~ value + capital, data = pggr, method = "OLS")
fm_pols <- systemfit(invest ~ value + capital, data = pggr, method = "OLS", pooled = TRUE)
## or "by hand"
fm_gm <- lm(invest ~ value + capital, data = ggr, subset = firm == "General Motors")
mean(residuals(fm_gm)^2)   ## Greene uses MLE
## etc.
fm_pool <- lm(invest ~ value + capital, data = ggr)

## Tab. 14.3 (and Tab 13.4, cross-section ML)
## (not run due to long computation time)
\dontrun{
fm_ml <- systemfit(invest ~ value + capital, data = pggr, method = "SUR",
  methodResidCov = "noDfCor", maxiter = 1000, tol = 1e-10)
fm_pml <- systemfit(invest ~ value + capital, data = pggr, method = "SUR", pooled = TRUE, 
  methodResidCov = "noDfCor", residCovWeighted = TRUE, maxiter = 1000, tol = 1e-10)
}

## Fig. 14.2
plot(unlist(residuals(fm_sur)[, c(3, 1, 2, 5, 4)]), 
  type = "l", ylab = "SUR residuals", ylim = c(-400, 400), xaxs = "i", yaxs = "i")
abline(v = c(20,40,60,80), h = 0, lty = 2)


###################
## Klein model I ##
###################

## data
data("KleinI", package = "AER")

## Tab. 15.3, OLS
library("dynlm")
fm_cons <- dynlm(consumption ~ cprofits + L(cprofits) + I(pwage + gwage), data = KleinI)
fm_inv <- dynlm(invest ~ cprofits + L(cprofits) + capital, data = KleinI)
fm_pwage <- dynlm(pwage ~ gnp + L(gnp) + I(time(gnp) - 1931), data = KleinI)
summary(fm_cons)
summary(fm_inv)
summary(fm_pwage)
## Notes:
##  - capital refers to previous year's capital stock -> no lag needed!
##  - trend used by Greene (p. 381, "time trend measured as years from 1931")
##    Maddala uses years since 1919

## preparation of data frame for systemfit
KI <- ts.intersect(KleinI, lag(KleinI, k = -1), dframe = TRUE)
names(KI) <- c(colnames(KleinI), paste("L", colnames(KleinI), sep = ""))
KI$trend <- (1921:1941) - 1931

library("systemfit")
system <- list(
  consumption = consumption ~ cprofits + Lcprofits + I(pwage + gwage),
  invest = invest ~ cprofits + Lcprofits + capital,
  pwage = pwage ~ gnp + Lgnp + trend)

## Tab. 15.3 OLS again
fm_ols <- systemfit(system, method = "OLS", data = KI)
summary(fm_ols)

## Tab. 15.3 2SLS, 3SLS, I3SLS
inst <- ~ Lcprofits + capital + Lgnp + gexpenditure + taxes + trend + gwage
fm_2sls <- systemfit(system, method = "2SLS", inst = inst,
  methodResidCov = "noDfCor", data = KI)

fm_3sls <- systemfit(system, method = "3SLS", inst = inst,
  methodResidCov = "noDfCor", data = KI)

fm_i3sls <- systemfit(system, method = "3SLS", inst = inst,
  methodResidCov = "noDfCor", maxiter = 100, data = KI)


############################################
## Transportation equipment manufacturing ##
############################################

## data
data("Equipment", package = "AER")

## Example 17.5
## Cobb-Douglas
fm_cd <- lm(log(valueadded/firms) ~ log(capital/firms) + log(labor/firms),
  data = Equipment)

## generalized Cobb-Douglas with Zellner-Revankar trafo
GCobbDouglas <- function(theta)
 lm(I(log(valueadded/firms) + theta * valueadded/firms) ~ log(capital/firms) + log(labor/firms),
     data = Equipment)

## yields classical Cobb-Douglas for theta = 0
fm_cd0 <- GCobbDouglas(0)

## ML estimation of generalized model
## choose starting values from classical model
par0 <- as.vector(c(coef(fm_cd0), 0, mean(residuals(fm_cd0)^2)))

## set up likelihood function
nlogL <- function(par) {
  beta <- par[1:3]
  theta <- par[4]
  sigma2 <- par[5]

  Y <- with(Equipment, valueadded/firms)
  K <- with(Equipment, capital/firms)
  L <- with(Equipment, labor/firms)

  rhs <- beta[1] + beta[2] * log(K) + beta[3] * log(L)
  lhs <- log(Y) + theta * Y

  rval <- sum(log(1 + theta * Y) - log(Y) +
    dnorm(lhs, mean = rhs, sd = sqrt(sigma2), log = TRUE))
  return(-rval)
}

## optimization
opt <- optim(par0, nlogL, hessian = TRUE)

## Table 17.2
opt$par
sqrt(diag(solve(opt$hessian)))[1:4]
-opt$value

## re-fit ML model
fm_ml <- GCobbDouglas(opt$par[4])
deviance(fm_ml)
sqrt(diag(vcov(fm_ml)))

## fit NLS model
rss <- function(theta) deviance(GCobbDouglas(theta))
optim(0, rss)
opt2 <- optimize(rss, c(-1, 1))
fm_nls <- GCobbDouglas(opt2$minimum)
-nlogL(c(coef(fm_nls), opt2$minimum, mean(residuals(fm_nls)^2)))


############################
## Municipal expenditures ##
############################

## Table 18.2
data("Municipalities", package = "AER")
summary(Municipalities)


###########################
## Program effectiveness ##
###########################

## Table 21.1, col. "Probit"
data("ProgramEffectiveness", package = "AER")
fm_probit <- glm(grade ~ average + testscore + participation,
  data = ProgramEffectiveness, family = binomial(link = "probit"))
summary(fm_probit)


####################################
## Labor force participation data ##
####################################

## data and transformations
data("PSID1976", package = "AER")
PSID1976$kids <- with(PSID1976, factor((youngkids + oldkids) > 0,
  levels = c(FALSE, TRUE), labels = c("no", "yes")))
PSID1976$nwincome <- with(PSID1976, (fincome - hours * wage)/1000)

## Example 4.1, Table 4.2
## (reproduced in Example 7.1, Table 7.1)
gr_lm <- lm(log(hours * wage) ~ age + I(age^2) + education + kids,
  data = PSID1976, subset = participation == "yes")
summary(gr_lm)
vcov(gr_lm)

## Example 4.5
summary(gr_lm)
## or equivalently
gr_lm1 <- lm(log(hours * wage) ~ 1, data = PSID1976, subset = participation == "yes")
anova(gr_lm1, gr_lm)

## Example 21.4, p. 681, and Tab. 21.3, p. 682
gr_probit1 <- glm(participation ~ age + I(age^2) + I(fincome/10000) + education + kids,
  data = PSID1976, family = binomial(link = "probit") )
gr_probit2 <- glm(participation ~ age + I(age^2) + I(fincome/10000) + education,
  data = PSID1976, family = binomial(link = "probit"))
gr_probit3 <- glm(participation ~ kids/(age + I(age^2) + I(fincome/10000) + education),
  data = PSID1976, family = binomial(link = "probit"))
## LR test of all coefficients
lrtest(gr_probit1)
## Chow-type test
lrtest(gr_probit2, gr_probit3)
## equivalently:
anova(gr_probit2, gr_probit3, test = "Chisq")
## Table 21.3
summary(gr_probit1)

## Example 22.8, Table 22.7, p. 786
library("sampleSelection")
gr_2step <- selection(participation ~ age + I(age^2) + fincome + education + kids, 
  wage ~ experience + I(experience^2) + education + city,
  data = PSID1976, method = "2step")
gr_ml <- selection(participation ~ age + I(age^2) + fincome + education + kids, 
  wage ~ experience + I(experience^2) + education + city,
  data = PSID1976, method = "ml")
gr_ols <- lm(wage ~ experience + I(experience^2) + education + city, 
  data = PSID1976, subset = participation == "yes")
## NOTE: ML estimates agree with Greene, 5e errata. 
## Standard errors are based on the Hessian (here), while Greene has BHHH/OPG.



####################
## Ship accidents ##
####################

## subset data
data("ShipAccidents", package = "AER")
sa <- subset(ShipAccidents, service > 0)

## Table 21.20
sa_full <- glm(incidents ~ type + construction + operation, family = poisson,
  data = sa, offset = log(service))
summary(sa_full)

sa_notype <- glm(incidents ~ construction + operation, family = poisson,
  data = sa, offset = log(service))
summary(sa_notype)

sa_noperiod <- glm(incidents ~ type + operation, family = poisson,
  data = sa, offset = log(service))
summary(sa_noperiod)

## model comparison
anova(sa_full, sa_notype, test = "Chisq")
anova(sa_full, sa_noperiod, test = "Chisq")

## test for overdispersion
dispersiontest(sa_full)
dispersiontest(sa_full, trafo = 2)


######################################
## Fair's extramarital affairs data ##
######################################

## data
data("Affairs", package = "AER")

## Tab. 22.3 and 22.4
fm_ols <- lm(affairs ~ age + yearsmarried + religiousness + occupation + rating,
  data = Affairs)
fm_probit <- glm(I(affairs > 0) ~ age + yearsmarried + religiousness + occupation + rating,
  data = Affairs, family = binomial(link = "probit"))

fm_tobit <- tobit(affairs ~ age + yearsmarried + religiousness + occupation + rating,
  data = Affairs)
fm_tobit2 <- tobit(affairs ~ age + yearsmarried + religiousness + occupation + rating,
  right = 4, data = Affairs)

fm_pois <- glm(affairs ~ age + yearsmarried + religiousness + occupation + rating,
  data = Affairs, family = poisson)

library("MASS")
fm_nb <- glm.nb(affairs ~ age + yearsmarried + religiousness + occupation + rating,
  data = Affairs)

## Tab. 22.6
library("pscl")
fm_zip <- zeroinfl(affairs ~ age + yearsmarried + religiousness + occupation + rating | age + 
  yearsmarried + religiousness + occupation + rating, data = Affairs)


######################
## Strike durations ##
######################

## data and package
data("StrikeDuration", package = "AER")
library("MASS")

## Table 22.10
fit_exp <- fitdistr(StrikeDuration$duration, "exponential")
fit_wei <- fitdistr(StrikeDuration$duration, "weibull")
fit_wei$estimate[2]^(-1)
fit_lnorm <- fitdistr(StrikeDuration$duration, "lognormal")
1/fit_lnorm$estimate[2]
exp(-fit_lnorm$estimate[1])
## Weibull and lognormal distribution have
## different parameterizations, see Greene p. 794

## Example 22.10
library("survival")
fm_wei <- survreg(Surv(duration) ~ uoutput, dist = "weibull", data = StrikeDuration)
summary(fm_wei)
}
}

\keyword{datasets}
