Results 1 to 6 of 6

Math Help - Consider a random sample of 10 patients..

  1. #1
    Banned
    Joined
    Dec 2008
    From
    Mauritius
    Posts
    523

    Consider a random sample of 10 patients..

    Question : Consider a random sample of 10 patients using a drug A for headache remedy yields sample mean and variance as 12.3 minutes and 6.54 minutes, while a random sample of 10 other patients using drug B gives sample mean and variance as 10.1 minutes and 4.1 minutes. Find a 95% confidence interval for the true difference in the mean relief times.

    --------------------------My work ---------------------------

    n_1 = 10
    \bar x_1 = 12.3

    \sigma^2 _1 = 6.54

    n_2 = 10
     \bar x_2 = 10.1

     \sigma^2 _2 = 4.1

    \alpha = 0.05 degree of freedom = 0.95

    t = \frac{x_1 - x_2}{\sqrt{\frac{\sigma^2 _ 1}{n_1} + \frac{\sigma^2 _2}{n_2}}}


    Is this correct what i am trying to do ???
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor matheagle's Avatar
    Joined
    Feb 2009
    Posts
    2,763
    Thanks
    5
    it's not bad
    BUT those seem to be sample and not population variances.
    There are two cases.
    Most people assume the POPULATION variances are equal.
    In that case you POOL the twho sample variances.
    That would give you a t distribution with 10+10-2 degrees of freedom.

    That also looks more like a test statistic, which you can pivot on and slove for the pop means.

    Here is the case when you do NOT assume equal pop variances...http://en.wikipedia.org/wiki/Welch's_t_test

    \bar X_1 -\bar X_2\pm t{\sqrt{\frac{S^2 _ 1}{n_1} + \frac{S^2 _2}{n_2}}}

    Here is the other case

    \bar X_1 -\bar X_2\pm tS_P{\sqrt{\frac{1}{n_1} + \frac{1}{n_2}}}
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Banned
    Joined
    Dec 2008
    From
    Mauritius
    Posts
    523
    So mite which one is the correct one to use for this problem
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by zorro View Post
    So mite which one is the correct one to use for this problem
    That is your decision to make. Perhaps after a discussion with your instructor.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    MHF Contributor matheagle's Avatar
    Joined
    Feb 2009
    Posts
    2,763
    Thanks
    5
    Btw, what is a mite?
    Mite - Wikipedia, the free encyclopedia
    ewwwwww
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Banned
    Joined
    Dec 2008
    From
    Mauritius
    Posts
    523
    u have atlast got it mite
    cheers on a new discovery
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. A random sample X
    Posted in the Statistics Forum
    Replies: 4
    Last Post: January 1st 2010, 02:24 AM
  2. Random sample
    Posted in the Advanced Statistics Forum
    Replies: 0
    Last Post: January 10th 2009, 03:23 AM
  3. Random Sample
    Posted in the Advanced Statistics Forum
    Replies: 1
    Last Post: August 2nd 2008, 05:57 AM
  4. Random sample
    Posted in the Advanced Statistics Forum
    Replies: 1
    Last Post: May 8th 2008, 08:21 PM
  5. Sample Random Sample Question 2
    Posted in the Advanced Statistics Forum
    Replies: 2
    Last Post: January 7th 2008, 07:58 AM

Search Tags


/mathhelpforum @mathhelpforum