Hall-life of IgG S1 titers after covid

How to calcular it on longitudinal data basis ?
Could any one know how to performance analysis of paper dan et al., science 381, 587( 2021) ???

Hello @Ana6 ,

I don't think this is the best forum to ask a question like yours.
The welcome message shows you what to expect of the community.

The drc-package (Dose-response-curve) may be helpful for that: