Aaron, I searched ?scran::pairwiseTTests as well as the code on GitHub but could not find out whether the lfc argument and corresponding output column prefixed with logFC was log2 or natural log. I assume that it is base 2 as the limma output. Thanks in advance! Chris

It's the same base as the log-transformation that was used to create the assay.type. If you were following the standard workflow using, e.g., scater::normalize, then yes, this would be base 2. If you did your own thing, then it's whatever base you used to compute the input x. I'll mention this explicitly in the documentation.