This function calculates the immunoglobulin A (IgA) Index as defined in Kau et al. (2015, 10.1126/scitranslmed.aaa4877) for a single taxon in a single sample.
The abundance of the bacteria in the IgA positive/high fraction (abundances should sum to 1 not as a %).
negabund
The abundance of the bacteria in the IgA negative/low fraction (abundances should sum to 1 not as a %).
pseudo
Pseudo count added to both the IgA positive and negative fraction values prior to calculation. Defaults to 1e-5. Recommend setting to minimum observed abundance in whole dataset.
nazeros
Return NA if the pos and neg abundances are both zero. Default is TRUE.
Value
A numeric value for the Kau index as defined in Kau et al. (2015, 10.1126/scitranslmed.aaa4877).