LR.VAR: Total logratio variance

In easyCODA: Compositional Data Analysis in Practice

Total logratio variance

Description

Computation of total (weighted)logratio variance.

Usage

LR.VAR(LRdata, row.wt = NA, weight=TRUE, vars=FALSE)

Arguments

LRdata	Matrix of logratios, either a vector or preferably the logratio object resulting from one of the functions ALR, CLR, PLR or LR
row.wt	Optional set of row weights (default: equal weights)
weight	Logical indicating if varying weights are returned(default:TRUE). If FALSE, unweighted (equal) weights are returned. Alternatively a set of positive weights can be specified.
vars	If TRUE, output individual variances as well (default FALSE)

Details

The function LR.VAR computes the sum of the logratio variances provided as input, using the weights in the logratio data object.

Value

LRtotvar	The total logratio variance
LRvars	(optional, if vars=TRUE, the individual logratio variances composing the total)

Author(s)

Michael Greenacre

References

Aitchison, J. (1986), The Statistical Analysis of Compositional Data, Chapman & Hall.
Greenacre, M. (2018), Compositional Data Analysis in Practice, Chapman & Hall / CRC Press.

See Also

LR, ALR, invALR, CLR, invCLR

Examples

data(cups)
# These give identical total logratio variances (weighted, by default)
LR.VAR(CLR(cups))
LR.VAR(LR(cups))
# Summing over all sets of ALRs gives twice the variance
totvar <- 0
for(j in 1:ncol(cups)) totvar <- totvar + LR.VAR(ALR(cups, denom=j))
totvar/2

easyCODA documentation built on Sept. 11, 2024, 5:33 p.m.