1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Sample statistics vs population statistics

  1. Mar 21, 2012 #1


    User Avatar

    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] :-)
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook