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← Sum of Squares - Intro to Descriptive Statistics

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

  1. Well this one means that you're squaring each of these values, and then adding
  2. them up. Which isn't what we're doing here. Here we're adding up the squared
  3. deviations. For this one you really have to be careful about having parentheses
  4. or no parentheses. Because this means that we only sum up the values, all of
  5. these, and then we subtract the squared mean, which isn't what we did. Again,
  6. here parenthesis are important. This means that we sum up all the values, then
  7. we subtract the mean, and then we square the result. That's not what we did.
  8. This one doesn't have a summation sign, which means that we take some arbitrary
  9. value, unspecified. So like $38,801, for example. And then we subtract the mean.
  10. And then we square the results. And that's again, not what we did. But this one
  11. says that you take this, which is each value, minus the mean, to get the
  12. deviation. You square each deviation, and then you add them all up. So this is
  13. the correct formula for adding these up. This is called SS, for sum of squares.