This module calculates confidence intervals for ratios of counts. It is specially designed for environmental indices based on microfossil counts in paleontology, on the form (a+c) / (b+c). This general formula covers the common cases a/b, where c=0, and c / (b+c), where a=0. No data are required in the spreadsheet.
Two methods are provided, as described by Suchéras-Marx et al. (2019). The first is a Monte Carlo procedure based on a transformation of the normal distribution. The second is a straightforward bootstrap, with two versions (simple, which can produce negative values), and percentile. For details see also the Past manual.
Reference
Suchéras-Marx, B., Escarguel, G., Ferreira, J. & Hammer, Ø. 2019. Statistical confidence intervals for relative abundances and abundance-based ratios: simple practical solutions for an old overlooked question. Marine Micropaleontology 151:101751.