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Getting Help
Roger D. Peng, Associate Professor of Biostatistics
Johns Hopkins Bloomberg School of Public Health
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selfcontained

Asking Questions

  • Asking questions via email is different from asking questions in person
  • People on the other side do not have the background information you have
    • they also don’t know you personally (usually)
  • Other people are busy; their time is limited
  • The instructor (me) is here to help in all circumstances but may not be able to answer all questions!

Finding Answers

  • Try to find an answer by searching the archives of the forum you plan to post to.
  • Try to find an answer by searching the Web.
  • Try to find an answer by reading the manual.
  • Try to find an answer by reading a FAQ.
  • Try to find an answer by inspection or experimentation.
  • Try to find an answer by asking a skilled friend.
  • If you're a programmer, try to find an answer by reading the source code.

Asking Questions

  • It’s important to let other people know that you’ve done all of the previous things already
  • If the answer is in the documentation, the answer will be “Read the documentation”
    • one email round wasted

Example: Error Messages

> library(datasets) 
> data(airquality) 
> cor(airquality)
Error in cor(airquality) : missing observations in cov/cor

Google is your friend


Asking Questions

  • What steps will reproduce the problem?
  • What is the expected output?
  • What do you see instead?
  • What version of the product (e.g. R, packages, etc.) are you using?
  • What operating system?
  • Additional information

Subject Headers

  • Stupid: "Help! Can't fit linear model!"
  • Smart: "R 3.0.2 lm() function produces seg fault with large data frame, Mac OS X 10.9.1"
  • Smarter: "R 3.0.2 lm() function on Mac OS X 10.9.1 -- seg fault on large data frame"

Do

  • Describe the goal, not the step
  • Be explicit about your question
  • Do provide the minimum amount of information necessary (volume is not precision)
  • Be courteous (it never hurts)
  • Follow up with the solution (if found)

Don't

  • Claim that you’ve found a bug
  • Grovel as a substitute for doing your homework
  • Post homework questions on mailing lists (we’ve seen them all)
  • Email multiple mailing lists at once
  • Ask others to debug your broken code without giving a hint as to what sort of problem they should be searching for

Case Study: A Recent Post to the R-devel Mailing List

Subject: large dataset - confused 
Message:
  I'm trying to load a dataset into R, but
    I'm completely lost. This is probably
    due mostly to the fact that I'm a
    complete R newb, but it's got me stuck
    in a research project.

Response

Yes, you are lost. The R posting guide is
  at http://www.r-project.org/posting-
  guide.html and will point you to the
  right list and also the manuals (at
  e.g. http://cran.r-project.org/
  manuals.html, and one of them seems
  exactly what you need).

Analysis: What Went Wrong?

  • Question was sent to the wrong mailing list (R-devel instead of R-help)
  • Email subject was very vague
  • Question was very vague
  • Problem was not reproducible
  • No evidence of any effort made to solve the problem
  • RESULT: Recipe for disaster!

Places to Turn

  • Class discussion board; your fellow students
  • r-help@r-project.org
  • Other project-specific mailing lists (This talk inspired by Eric Raymond’s “How to ask questions the smart way”)
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