Results 1 to 5 of 5

Math Help - Confidence Intervals

  1. #1
    Newbie
    Joined
    Feb 2010
    Posts
    12

    Confidence Intervals

    Find the minimum sample size that is required to estimate the proportion within 5% of the true proportion with 98% confidence.

    a. 9

    b. 8

    c. 397

    d. 307
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Aug 2007
    From
    USA
    Posts
    3,111
    Thanks
    2
    How big is the population? If we need a Finite Population correction Factor, we'll need to know that piece of information..
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Feb 2010
    Posts
    12
    Quote Originally Posted by TKHunny View Post
    How big is the population? If we need a Finite Population correction Factor, we'll need to know that piece of information..
    TKHunny how I posted the question is the all the information that was on the sheet. It didn't say how big the population was.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor
    Joined
    Aug 2007
    From
    USA
    Posts
    3,111
    Thanks
    2
    Bad question. Needs more information.

    Typically, (z^2 * s^2)/(d^2), so (1.96^2) * p*(1-p) / (0.025^2)

    To be conserative, [(1.96^2) * (1/2)^2] / (0.025^2)

    I was once a consultant in a legal dispute where this was important. The client was asking the wrong people. The entire population that required research was around 500, but it was VERY expensive to research even one case. We needed to know how many to sample to see if we REALLY needed to research EVERY case. The first three people who tried to answer the question said the SMALLER sample had to be OVER 500 - more than the entire population! As this made no sense, they kept looking for the answer. Fortunately, more rational estimates were obtained by the introduction of the Finite Population Correction Factor. 13 or 14 as I recall.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Junior Member
    Joined
    Oct 2010
    Posts
    36
    I'd probably assume the population is effectively infinite since it doesn't give the actual N value, not indicate a FPC is required.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Confidence Intervals...
    Posted in the Statistics Forum
    Replies: 1
    Last Post: April 21st 2010, 11:41 PM
  2. confidence intervals
    Posted in the Advanced Statistics Forum
    Replies: 2
    Last Post: April 13th 2010, 08:31 AM
  3. Confidence Intervals
    Posted in the Advanced Statistics Forum
    Replies: 2
    Last Post: June 17th 2009, 05:28 AM
  4. Confidence Intervals
    Posted in the Statistics Forum
    Replies: 0
    Last Post: May 26th 2009, 07:53 AM
  5. Confidence Intervals
    Posted in the Advanced Statistics Forum
    Replies: 0
    Last Post: June 16th 2008, 08:12 AM

Search Tags


/mathhelpforum @mathhelpforum