resolution.uncertainty.abs: Compute the resolution uncertainty (last digit influence) -...

In claus-e-andersen/clanTools: R functions of general use for data analysis and presentation

Description

This function compute the standard uncertainty (k=1) for instruments with a given number of digits (say, 4) that is always used to their fullest extend (i.e. a reading of 1 would actually be 1.000 and a reading of 1.1E-9 would actually be 1.100 x 1E-9).

The function handles zero-readings.

We compute the standard uncertainty from resolution limitations as the last digit divided by the squareroot of 12 (i.e. u = 0.29 * step). This is consistent with GUM F.2.2.1 and the assumption of a uniform probability distribution. So, with four digits, a reading starting with 1 (like 1.002) will lead to an estimated standard uncertainty of about 2.9e-4. Note that we assume that the instrument always provides the given number of digits.

See also: resolution.uncertainty.pct

#' Example:

resolution.uncertainty.abs(0,digits=4,last.digit.step=1)

resolution.uncertainty.abs(1.1e-20,digits=4,last.digit.step=1)

resolution.uncertainty.abs(1.1e20,digits=4,last.digit.step=1)

Note that the function is vectorized, such that calls like the following is possible:

resolution.uncertainty.abs(c(1.2, 1.3, 0, 0, NA, NA, 2), digits=4,last.digit.step=1)

Usage

resolution.uncertainty.abs(1004,digits=4,last.digit.step=1)

Arguments

x	raw reading (can be vectorized).
digits	number of digits on the instrument display.
last.digit.step	resolution of last digit (e.g. 1 or 5).
min.value	do not report an uncertainty below this value (e.g. 0.001 in abs. units).
max.value	do not report an uncertainty above this value (e.g. 50 in abs. units).

Value

numeric value (absolute uncertainty). May be vectorixed.

Author(s)

Claus E. Andersen

claus-e-andersen/clanTools documentation built on Oct. 23, 2020, 7:59 a.m.