screening {LoBrA}

Screening of background or confounding components

Description

Background noise signals originating from experimental settings or random events can hugely influence the signal pattern of the breath. Background data enables the detailed evaluation and differentiation of the compounds originating primarily from the background or confounding factors as compared to those from the sample itself. The method assumes that all compounds of interest show a larger variation in the sample as compared to the background noise.

Usage

screening(
  ldo,
  method = c("bf", "levene", "bartlett"),
  alpha = 0.05,
  criteria = c(1, 1)
)

Arguments

ldo

Longitudinal Data Object

method

list of tests to perform, standard values: 'bf', 'levene' or 'bartlett'). 'bf' relates to "Brown-Forsythe" Levene-type procedure, 'levene' uses classical "Levene's" procedure and 'bartlett' applies Bartlett's test.

alpha

A numeric value to defining the cutoff to select peaks.

criteria

indicators which criteria to use for screening decision.

Value

Returns an object of type 'LDOscreening' containing the original 'ldo' object and the results of the screening. The variable 'selectedPeaks' contains a matrix including the results (TRUE = Significant, FALSE = not Significant) of the specified tests ('bf', 'levene', 'bartlett').

Examples

## Not run: 
 

  data(LoBraExample)
  method= c('bf', 'levene', 'bartlett')
  alpha =0.05
  criteria=c(1,1)
  ldos<-screening(ldo, method, alpha, criteria)
  components <- ldos@selectedPeaks[,"levene"]
  components <- names(components)[components]
  selectedLDO <- selectComponents(ldo, components)