Conclusions

• Lessons learned:
  • rounding has an effect, especially for large data sets
  • if you are interested in the "real" numbers
    • use small data sets
    • use qualitative tools (e.g. Q-Q plot)
    • use adapted methods
  • read "Interval Estimation of a Normal Process Mean from Rounded Data" by Lee and Vardeman
• General lessons:
  • numerical experiments help to
    • find facts
    • test ideas
    • identify relevant parameters
  • "much data is better" is not always true
  • "reasonable" assumptions or approximations might be wrong
  • always question everything - even if it has been used for decades
• Is body height really normally distributed?
  • of course not, it is always positive
    • but: this is irrelevant in our example
  • it has to be measured → values are always rounded
    • but: you can always increase the precision
  • it varies in time - you are larger in the morning
    • but: you could define h(t)
  • "body height" doesn't exist
    • where is the upper limit of your body?
    • ask the highest electron
    • don't forget Heisenberg!