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← Jelly Beans - Intro to Descriptive Statistics

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Showing Revision 3 created 05/24/2016 by Udacity Robot.

  1. >> Here's another way to look at it. Let's say you have a bag of jellybeans.
  2. There's only one licorice, but there are four strawberries and four blueberries.
  3. There's also only one cherry and two lime, or lemon, I don't know, you decide.
  4. If we take a sample of, say, four Jelly Bellies, most likely, we're not going to
  5. get the licorice one. Say we just get these in our sample. This sample doesn't
  6. show the whole range of Jelly Belly flavors that we have, including cherry and
  7. licorice. So our sample underestimates the variability in our Jelly Belly
  8. population. Hopefully, this example lends a little more insight into why we
  9. divide by n minus 1 when calculating the standard deviation of a sample. But
  10. please let's discuss it in the forums. There, we could go into a lot more depth.
  11. For the purposes of this class though, as long as you have a basic intuitive
  12. understanding of the difference between sample standard deviation and population
  13. standard deviation, then you'll be fine.