Results 1 to 2 of 2

Math Help - Stratified Sampling

  1. #1
    Newbie
    Joined
    Sep 2013
    From
    U.S.A.
    Posts
    8

    Stratified Sampling

    A city has 90000 dwellings: 35000 are homes, 45000 are apartments, 10,000 are condos.


    i) You know the mean electricity use is roughly twice as much for homes as
    for apartments or condos, and the standard deviation is proportional
    to the mean so S_1 = 2S_2 = 2S_2. How would you distribute a stratified sample
    of 900 observations if you wanted to approximate the mean electricity usage
    for all homes in the city?


    ii)Now imagine that you take a stratified random sample with proportional allocation
    and want to estimate the overall proportion of households in which energy
    conservation is practiced. If 45% of homes, 25% of apartment,
    and 3% of condos practice conserving energy, what is p for the
    population? What gain would the stratified sample with proportional allocation
    offer over an SRS, that is, what is \frac{V_{prop}({\hat{p_{str}}})}{V_{SRS}{(\hat{p_{  SRS}}})}?


    Solutions:


    i. Not sure how to allocate the sample.


    ii. I found p = .303333, however, I am unable to solve for s^2 = \frac{n}{n-1}p(1-p). This is necessary to complete the problem.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Newbie
    Joined
    Sep 2013
    From
    U.S.A.
    Posts
    8

    Re: Stratified Sampling

    Sorry, should read S_1 = 2S_2 = 2S_3
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Probability Sampling and Sampling Methods
    Posted in the Advanced Statistics Forum
    Replies: 3
    Last Post: March 16th 2011, 05:41 AM
  2. Stratified vs. Cluster Sampling
    Posted in the Statistics Forum
    Replies: 0
    Last Post: October 28th 2010, 02:54 PM
  3. stratified sampling
    Posted in the Statistics Forum
    Replies: 2
    Last Post: May 29th 2010, 05:32 AM
  4. stratified sampling
    Posted in the Statistics Forum
    Replies: 2
    Last Post: April 30th 2010, 12:29 PM
  5. Stratified Sampling
    Posted in the Statistics Forum
    Replies: 4
    Last Post: March 17th 2008, 11:31 AM

Search Tags


/mathhelpforum @mathhelpforum