gx.triples.fgx: ANOVA to Estimate if 'Triples' are a Valid Subset

In rgr: Applied Geochemistry EDA

Description

Function to execute a simple ANOVA to determine if the Field Duplicates are a valid subset of the regional coverage samples, and if the Field Duplicates pairs have ‘equivalent’ variability. Optionally the data may be logarithmically (base 10) transformed.

Usage

gx.triples.fgx(x, RepStat, xname = deparse(substitute(x)),
	log = FALSE)

Arguments

x	a file of regional coverage and field duplicate data.
RepStat	the Replicate Status code, see below.
xname	by default the character string for the data file name, x, is used for the table title. An alternate title can be displayed with xname = "text string", see Examples.
log	if a logarithmic transformation of the data is required to meet homogeneity of variance considerations (i.e. severe heteroscedasticity) set log = TRUE. This is also advisable if the range of the observations exceeds 1.5 orders of magnitude.

Note

RepStat (Replicate Status) is a code used within the National Geochemical Reconnaissance protocol that indicates an individual geochemical sample's position in the QA/QC structure. 0 indicates a routine survey sample; 1 indicates a routine survey sample which has an associated duplicate sample; and 2 indicates that duplicate sample.

Any less than detection limit values represented by negative values, or zeros or other numeric codes representing blanks in the data, must be removed prior to executing this function, see ltdl.fix.df.

Any NAs in the data must also be removed prior to running the triples.fgx function. This requires care as the data must be in complete duplicate sets.

Author(s)

Robert G. Garrett

References

Garrett, R.G., 2013. Assessment of local spatial and analytical variability in regional geochemical surveys with a simple sampling scheme. Geochemistry: Exploration, Environment, Analysis, 13(4):349-354, doi 10.1144.geochem2011-085.

See Also

ltdl.fix.df, remove.na, triples.test1, gx.triples.fgx, triples.test2

Examples

## Make test data available
data(triples.test2)
attach(triples.test2)

## Carry out ANOVAs for equivalence of variances
gx.triples.fgx(Ba_ppm, RS, xname = 
"Ba (mg/kg - Aqua Regia digestion) in <2 mm unmilled C-horizon soil")

## Detach test data
detach(triples.test2)

rgr documentation built on May 2, 2019, 6:09 a.m.