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Math Help - Two Sample T-Test

  1. #1
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    Two Sample T-Test

    I have a t-test question that I need help with.


    This is the information that has been given to me.


    Male Female
    m=41 n=17

    x(bar) =69.2 y(bar)= 66.7

    S(x)=2.66 S(y)= 2.34

    Test to see whether the difference between mean male and female is 5.5 inches.
    I got the test statistic which was 3.57, and the pooled estimate variance to be 2.57


    The problem is i cant get the p value, i dont understand where i am meant to look in the tables.

    In my book it says the forumula to get the P-Value is: P=2*P(T>|t|) ,where t is observed value.

    Any help please

    Thomas
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  2. #2
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    Re: Two Sample T-Test

    Quote Originally Posted by thomasboateng View Post
    I have a t-test question that I need help with.


    This is the information that has been given to me.


    Male Female
    m=41 n=17

    x(bar) =69.2 y(bar)= 66.7

    S(x)=2.66 S(y)= 2.34

    Test to see whether the difference between mean male and female is 5.5 inches.
    I got the test statistic which was 3.57, and the pooled estimate variance to be 2.57


    The problem is i cant get the p value, i dont understand where i am meant to look in the tables.

    In my book it says the forumula to get the P-Value is: P=2*P(T>|t|) ,where t is observed value.

    Any help please

    Thomas
    What is your test statistic? What are the number of degrees of freedom?

    See this site for more information.

    CB
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  3. #3
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    Re: Two Sample T-Test

    I still dont get it,

    my test statistic is 3.37. not sure what my degrees of freedom are?
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    Re: Two Sample T-Test

    Quote Originally Posted by thomasboateng View Post
    I still dont get it,

    my test statistic is 3.37. not sure what my degrees of freedom are?
    Read the material on the link I gave you.

    CB
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  5. #5
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    Re: Two Sample T-Test

    yes the degrees of freedom is 56 for me

    but in the example its 66 and its cv is

    If using 2-tailed test

    Alpha.05, tcv= 1.997

    it just tells me the cv is 1.997 is it always going to be 1.997 ?

    Thomas
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  6. #6
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    Re: Two Sample T-Test

    Thomas,

    Yes you are correct it is always going to be 1.997 for two sample t tests.

    Luke
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    Re: Two Sample T-Test

    Quote Originally Posted by thomasboateng View Post
    yes the degrees of freedom is 56 for me

    but in the example its 66 and its cv is

    If using 2-tailed test

    Alpha.05, tcv= 1.997

    it just tells me the cv is 1.997 is it always going to be 1.997 ?

    Thomas
    No you need to look up the cumulative t-distribution with 56 degrees of freedom for a critical value of 0.975, which will give t_cv=2.004 rather than the t_cv=1.997 for 66 degrees of freedom.

    (You may have a table of critical values for t-tailed tests then you would look up the critical value that corresponds to 0.95 probability of the t-score being between +/- t_cv)

    CB
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    Re: Two Sample T-Test

    Quote Originally Posted by lukeheselden View Post
    Thomas,

    Yes you are correct it is always going to be 1.997 for two sample t tests.

    Luke
    This is wrong, see my other post.

    CB
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