The important thing is to add error bars, which has probably been in XKCD passim. Yes, you want the numbers, but I've quite often just digitized plots from pape

The important thing is to add error bars, which has probably been in XKCD passim. Yes, you want the numbers, but I've quite often just digitized plots from papers. I wrote a program for inverse plotting with an HP flatbed sometime in the '80s.