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Need some clarification with statistics

  1. Nov 2, 2009 #1
    Im currently doing an introductory stats course and have learnt:

    - poisson distribution
    - binomial distribution
    - normal distribution
    - t-student
    - and chi-square

    I think I know what most of them look like but am having a bit of a hard time distinguishing what distribution to use when faced with questions.

    Heres my current understanding:

    - poisson distribution - when pop mean is given over an interval?
    - binomial distribution - when given sample size and p of success
    - normal distribution - n >30 or if normal
    - t-student - when population is normal distributed but variance parameter is unknown
    - and chi-square - not too sure when to use.

    Wondering if anyone can help me with my current problems, thanks in advance!
  2. jcsd
  3. Nov 3, 2009 #2
    the normal distrubuted population's random estimated variance is chi square distribute, when you ask what probability you can obtain a variance you need chi square.
  4. Nov 3, 2009 #3
    Firstly, is the goal here to pass the exam or to learn statistics?
  5. Nov 3, 2009 #4
    To learn statistics, im already doing well enough to pass the exam. Im probably going to learn much more difficult concepts in the future so its best if i get the fundamentals right.
  6. Nov 4, 2009 #5
    The key is understanding what assumptions are reasonable for the given data, and which are necessary in order to use a particular distribution in your repertoire. There aren't any fixed rules as to what applies when, but as you learn more distributions and see the various ways they arise you'll gain a more intuitive understanding of which candidates are most suitable for each situation.

    Good luck with your studies!
  7. Nov 5, 2009 #6
    thanks for pointing out the obvious.
  8. Nov 5, 2009 #7
    Glad you appreciate the point - many don't, which is why so much dodgy research gets published.

    Regarding the original questions, it sounds like you're on the right track except maybe the Poisson distribution - not sure what you meant by "pop mean is given over an interval", did you mean to say "average occurrence rate is given over an interval"?
  9. Nov 5, 2009 #8
    Yeah i think i understand poisson distribution more clearly now, just finished the course today probably planning to learn more chunkier stats in the future.
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