Single variable deletions from the uncertainty budget.
Description
drop1
calculates revised combined uncertainty for single variable deletions from
an object of class 'uncert'.
Usage
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15  ## 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 
which 
logical; controls the form of information returned when

x 
An object of class ‘drop1.uncert’ returned by 
... 
Further objects passed to other functions. 
digits 
number of digits used to format the output. See the 
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. A plot for each value in which
is produced. 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)
.
Author(s)
S. L. R. Ellison, s.ellison@lgc.co.uk
References
None.
See Also
uncert
, uncertclass
, format
for digits
,
barplot
for available plot parameters.
Examples
1 2 3 4 5 6 7 8 9 10 11 12 13 