Results 1 to 2 of 2

Math Help - t-test and normality

  1. #1
    Junior Member
    Joined
    Oct 2010
    Posts
    37

    t-test and normality

    I keep reading that in order for a t-test to be valid the data need to be normal. I have distributions which are clearly skewed to the right (long right tails) so they are not normal. However I have a sample of of n>100 in both bases so the sampling distributions are essentially normal.

    My question therefore is: does the t-test requirement for normality refer to the original distributions for the raw data, or for the sampling distributions for the sample means?

    Thanks
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Master Of Puppets
    pickslides's Avatar
    Joined
    Sep 2008
    From
    Melbourne
    Posts
    5,236
    Thanks
    28

    Re: t-test and normality

    The t-test itself, tests the sample mean, which will be normally distributed.

    If your data itself is skewed but n is large enough the t-test is considered a robust test.

    I would recommend using a t-test and then using a different test, maybe a non-parametric test like the Kolmogorov-Smirnov test.

    Are the data sets considered different in both tests?
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Confidence intervals and assumption of normality
    Posted in the Statistics Forum
    Replies: 2
    Last Post: May 20th 2011, 03:32 AM
  2. Replies: 8
    Last Post: March 28th 2010, 06:45 PM
  3. Replies: 2
    Last Post: September 24th 2009, 09:02 AM
  4. Checking normality
    Posted in the Advanced Statistics Forum
    Replies: 0
    Last Post: April 5th 2009, 05:13 PM
  5. Normality
    Posted in the Advanced Algebra Forum
    Replies: 1
    Last Post: February 22nd 2008, 08:35 AM

Search Tags


/mathhelpforum @mathhelpforum