Sample size calculator for a national TB prevalence survey using a Shiny app

Sample size calculator based on chapter 5 of the TB prevalence survey handbook v2.

https://apps.who.int/iris/bitstream/handle/10665/44481/9789241548168_eng.pdf?sequence=1

NB: this is not for repeat surveys

This is a work in progress. I will make the app look prettier another time.