Statgen specific tutorial

[hyanwong]

The last one of the subaudience tutorials to tick off is the one for statistical geneticists. This issue can collect some ideas.

I have been chatting to Arni Gunnarson, and he suggested that the following topics would be of interest to a statgen researcher looking into tskit (here biased towards the ARGneedle - type approach, obviously)

• fast GRM calculation (see tskit's `genetic_relatedness()` versus eGRM (Fan et al. 2022) tskit#2603 - this is not ready yet though)
• Luke O'Connor / Wilder's "LDGM" stuff, now in Nature Genetics(!): https://www.nature.com/articles/s41588-023-01487-8
• putting phenotypes onto individuals in a tree sequence (e.g. Daiki's tstrait)
• once phenotypes are associated with individuals in a tree sequence:
  • fast calculation of heritability
  • ARG-informed association analysis similar to that in the ARGneedle paper