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← Same Scores - Intro to Descriptive Statistics

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Showing Revision 4 created 05/25/2016 by Udacity Robot.

  1. Now, the answer is no. Within the population of everyone who took the BBC test,
  2. you guys are a sample. There are a lot of different samples we could take of all
  3. the people that took the test. We can take big samples, and small samples. And,
  4. while your sample could get the same averages as those from the entire
  5. population. There will also be samples that don't have the same averages. The
  6. average memory score of the population is called the population parameter and
  7. it's denoted by mu. It's a funny little Greek symbol. And the average for the
  8. sample is called a sample statistic and we generally denote it by x bar. An x
  9. with a bar on top. Now, I want to stress, please don't be nervous about symbols.
  10. I know a lot of people get pretty nervous when they see symbols that they
  11. haven't seen before. But in mathematics, we really need symbols to illustrate
  12. our points. Think of it like, when you're playing a musical instrument, and you
  13. have sheep Sheet music.
  14. How else are we going to make sure that people in future generations learn these
  15. classical melodies? Sheet music is the best way to do that. And same with, in
  16. mathematics when we use symbols. We need to be able to articulate are thoughts
  17. to other people all around the world. And that's one things that's really cool
  18. about mathematics it's a universal language. So don't worry, you'll soon become
  19. familiar with these symbols because we're going to use them throughout this
  20. course. Now we can use this sample statistic to approximate the population
  21. parameter. But generally, they won't be exactly the same. The difference between
  22. these two is called the sampling error. Which means we can make educates guesses
  23. about population parameters using sample statistics, but we probably won't be
  24. 100% accurate. That's why it's really important to have a good sample that can
  25. better predict the population parameter. So going back the quiz, no. We don't
  26. think that the average scores for this class will be exactly the same. But it
  27. will probably come close, and we're going to be able to see that later.