Propagation of errors for isotope ratios

stat_SDprop function for propagation of descriptive and predictive (Poisson) error statistics for isotope ratios (R).

Usage

stat_SDprop(ion1, ion2, type = "sd", predicted = FALSE)

Arguments

ion1: A numeric vector constituting the single ion count rate of the heavy isotope if argument predicted is set to FALSE, otherwise counts are required.
ion2: A numeric vector constituting the single ion count rate of the light isotope if argument predicted is set to FALSE, otherwise counts are required.
type: A character string for the type of uncertainty estimate: "sd", standard deviation; "rsd", relative standard deviation in per mille; "se", standard error of the mean; "rse", relative standard error of the mean in per mille.
predicted: Logical indicating whether sd is descriptive FALSE, or based on predicted Poisson value TRUE.

Value

A numeric vector containing the propagated uncertainty of the isotope ratio.

Details

Isotope ratios are based on two measured variables, i.e., two isotopes of a single chemical species. The combined variable compounds the uncertainty associated with the individual measurement. Hence error propagation is required to obtain a reliable estimate of the uncertainty associated with the compounded variable (i.e. isotope ratio).

Examples

# Light isotope count rates
`32S` <- c(22318.19, 22151.20, 22429.52, 22143.78, 22574.25, 22455.50)

# Heavy isotope count rate
`34S` <- c(231.4838, 220.3725, 255.5584, 237.0395, 244.4471, 238.8914)

# Propagation
stat_SDprop(`34S`, `32S`, "rse")
#> [1] 18.41454