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Homework Help: Sample statistics vs population statistics

  1. Mar 21, 2012 #1

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    1. The problem statement, all variables and given/known data

    My task is to explain why the sample statistics I have obtained differ from the population statistics I have obtained from some data - using "concepts taught in class, if they exist". I have calculated x̄ and s, as well as σ and µ.

    2. Relevant equations

    First of all, the distribution is not normal, thus the emperical rule is invalid.

    3. The attempt at a solution

    Part of me thinks it's a trick question because there are very few "concepts" I can think of. The only thing I can come up with is that the mean differs because it is merely one sample, and according to the Central Limit Theorum, if I had a bigger sample space, the mean would be similar. Similarly, the standard deviation differs because it is merely one sample. Is this all there is to it or am I missing something?
     
  2. jcsd
  3. Mar 22, 2012 #2
    Sample statistics are obtained by sampling from a population. The idea is that the statistical properties of a population can (usually) be only estimated. In this respect, I slightly doubt about your data-based [itex]\mu, \sigma^2[/itex] :-)
     
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