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← Reading Tables 1 - Intro to Statistics

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Showing Revision 6 created 09/01/2016 by Franco Zearo.

  1. So here's a t-table that applies to statistical
  2. estimates with fewer than 30 samples. And the
  3. way to read through this on the left you see the degrees of freedom which is the
  4. number of samples minus 1. So if you have 10 samples it would be 9, if there are
  5. 15 samples it would be 14. On the top, you'll see 1 minus the confidence level.
  6. So if you want 95% confidence, you go to 0.05. If you
  7. want 98% confidence, you go to 0.02. Now there's a slight
  8. distinction here. There's a 1-tail and a 2-tails. So far, we've
  9. talked about 2-tails in which, we always cut off tails left
  10. and right of our confidence interval. There are occasions, which we'll
  11. talk about later, where we should just cut off one side.
  12. And those often occur in the context of testing
  13. hypotheses. Now for the time being, please just look
  14. at the 2-tails number over here. And ignore all
  15. those 1-tail numbers in this table. Okay? So just
  16. to make sure you know how to read this
  17. table. Suppose we have n=8 samples and we look
  18. for a 90% confidence interval. What number would you
  19. find in this table to be the magic number?