R: Single variable deletions from the uncertainty budget.
drop1.uncert
R Documentation
Single variable deletions from the uncertainty budget.
Description
drop1 calculates revised combined uncertainty for single variable deletions from
an object of class 'uncert'.
Usage
## S3 method for class 'uncert'
drop1(object, scope, simplify = TRUE,
which=c("% Change", "var", "u", "var.change", "u.change"), ...)
## S3 method for class 'uncertMC'
drop1(object, scope, simplify = TRUE,
which=c("% Change", "var", "u", "var.change", "u.change"), ...)
#Print and plot methods
## S3 method for class 'drop1.uncert'
print(x, ..., digits=2)
## S3 method for class 'drop1.uncert'
plot(x, ...,
which=c("% Change", "var", "u", "var.change", "u.change"))
Arguments
object
An object of class ‘uncert’ or ‘uncertMC’.
scope
character vector, expression or formula containing the list of
variables to be dropped. If missing, all variables in object$budget are taken
as scope.
simplify
logical. If simplify=TRUE, the return value is simplified to
a named vector. If FALSE, all forms available (see which) are
returned in a data frame.
which
logical; controls the form of information returned when simplify=TRUE.
Possible values are:
"var"
The modified values of u(y)^2.
"u"
The modified values of u(y).
"var.change"
The signed changes in u(y)^2.
"u.change"
The signed changes in u(y).
"% Change"
The percentage change in u(y).
x
An object of class ‘drop1.uncert’ returned by drop1.uncert.
...
Further objects passed to other functions.
digits
number of digits used to format the output. See the digits argument
of format.
Details
By analogy with drop1, drop1.uncert perfoms single variable deletions from
the uncertainty budget in object, calculates the resulting uncertainty and returns the
results in the form requested by simplify and which.
‘Single variable deletion’ of a variable x[i] is equivalent to setting the uncertainty
u(x[i]) to zero. Note that this also sets covariance terms involving x[i]
to zero. drop1.uncert does not support the deletion of single terms such as cov(i, j).
In the case of ‘uncertMC’ objects, drop1 currently requires object$MC$x to be
present (i.e. uncertMC called with keep.x=TRUE). The uncertMC
method does not support correlation.
For which="var.change", which="u.change" and which="% Change" the
change on dropping a variable is negative if the uncertainty reduces on removing the variable.
The print method simply prints the output with a header formed from the expr attribute
and with '%' appended to the "% Change" column.
The plot method produces a barplot of the chosen data column. Arguments in ‘...’ are passed to
barplot. If not already present in ‘...’ a default main title and ylab are used. The expr
attribute is shown as marginal text if not NA.
Value
If simplify=FALSE, an object of class ‘drop1.uncert’, consisting of a
data frame with row names corresponding to row.names(object$budget), columns
corresponding to all possible values of which in the order "var", "u", "var.change",
"u.change", "% Change", and an attribute expr containing a copy of the expr
value of the 'uncert' object to which drop1.uncert is applied.
If simplify=TRUE, the column of the above data frame corresponding to which
is returned as a vector with names row.names(object$budget).