Hi all .. there is no doubt a simple answer to this, but it eludes me.
In the first session below ( with jarque.bera.test) you will see that
p.value prints with a name of X-squared .
This is easily fixed by changing the source to assign a
more appropriate name - no name is assigned in the source listing
below (the original source code of jarque.bera.test() from tseries).. but
what I don't understand is how this (the name of X-squared) has arisen.
In the second session (with Box.test from ts) , p.value prints without
a name as I would expect .. the code looks superficially similar to me, so
obviously I am missing something.
wait a minute .. names seem to be inherited! yes. so this is really
more likely a minor glitch in jarque.bera.test due to assigning
names(STATISTIC) <- "X-squared"
too early, or omitting to assign a name to PVAL
I think I have it now.
thanks
>
> jbt<-jarque.bera.test(rnorm(1000))
> jbt$statistic
X-squared
1.575782 > jbt$p.value
X-squared
0.4548029 > jbt
Jarque Bera Test
data: rnorm(1000)
X-squared = 1.5758, df = 2, p-value = 0.4548
> jarque.bera.test
function (x)
{
if (NCOL(x) > 1)
stop("x is not a vector or univariate time series")
if (any(is.na(x)))
stop("NAs in x")
DNAME <- deparse(substitute(x))
n <- length(x)
m1 <- sum(x)/n
m2 <- sum((x - m1)^2)/n
m3 <- sum((x - m1)^3)/n
m4 <- sum((x - m1)^4)/n
b1 <- (m3/m2^(3/2))^2
b2 <- (m4/m2^2)
STATISTIC <- n * b1/6 + n * (b2 - 3)^2/24
names(STATISTIC) <- "X-squared"
PARAMETER <- 2
names(PARAMETER) <- "df"
PVAL <- 1 - pchisq(STATISTIC, df = 2)
METHOD <- "Jarque Bera Test"
structure(list(statistic = STATISTIC, parameter = PARAMETER,
p.value = PVAL, method = METHOD, data.name = DNAME),
class = "htest")
}
================ Box.test session =======================
>
> jbox<-Box.test(rnorm(1000))
> jbox$statistic
X-squared
3.609782 > jbox$p.value
[1] 0.05744064> jbox
Box-Pierce test
data: rnorm(1000)
X-squared = 3.6098, df = 1, p-value = 0.05744
> Box.test
function (x, lag = 1, type = c("Box-Pierce", "Ljung-Box"))
{
if (NCOL(x) > 1)
stop("x is not a vector or univariate time series")
DNAME <- deparse(substitute(x))
type <- match.arg(type)
cor <- acf(x, lag.max = lag, plot = FALSE)
n <- length(x)
PARAMETER <- lag
obs <- cor$acf[2:(lag + 1)]
if (type == "Box-Pierce") {
METHOD <- "Box-Pierce test"
STATISTIC <- n * sum(obs^2)
PVAL <- 1 - pchisq(STATISTIC, lag)
}
else {
METHOD <- "Box-Ljung test"
STATISTIC <- n * (n + 2) * sum(1/seq(n - 1, n - lag) *
obs^2)
PVAL <- 1 - pchisq(STATISTIC, lag)
}
names(STATISTIC) <- "X-squared"
names(PARAMETER) <- "df"
structure(list(statistic = STATISTIC, parameter = PARAMETER,
p.value = PVAL, method = METHOD, data.name = DNAME),
class = "htest")
}>
================== version info
> R.Version()
$platform
[1] "i386-pc-mingw32"
$arch
[1] "x86"
$os
[1] "Win32"
$system
[1] "x86, Win32"
$status
[1] ""
$major
[1] "1"
$minor
[1] "2.1"
$year
[1] "2001"
$month
[1] "01"
$day
[1] "15"
$language
[1] "R"
John Aitchison
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