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Thread: Sampling techniques and statistical bias

  1. #1 Sampling techniques and statistical bias 
    Forum Sophomore
    Join Date
    Sep 2005
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    106
    I am studying the math of 1-variable statistics and have some questions that I can't figure out. Can somebody kindly explain? I would really appreciate! :wink:

    1) A students' council is conducting a poll of students as they enter the cafeteria. Explain why this method is not appropriate for surveying students' opinions on "the location for the graduation prom"? What other sampling technique would be better?

    [I am guessing...is it because not everyone entering the cafeteria will graduate this year? And a better samling technique may be a simple random sample or systematic sample of all final year students? Am I right?]

    2) Classify the sampling method used in the following scenario:
    The province randomly chooses 25 public schools to participate in a new fundraising initiative.


    [Is it a simple random sample or a cluster sample? The answer in my book says cluster, but I don't understand why isn't this a simple random sample instead?]

    3) A survey uses a cluster sample of Vancouver (a city in Canada) residents to determine public opinion on whether the provincial government should increase funding for the public transit.

    [What type of bias is this? Can somebody please explain? I don't understand...]


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  3. #2 Re: Sampling techniques and statistical bias 
    Forum Freshman
    Join Date
    May 2005
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    53
    Quote Originally Posted by kingwinner
    1) A students' council is conducting a poll of students as they enter the cafeteria. Explain why this method is not appropriate for surveying students' opinions on "the location for the graduation prom"? What other sampling technique would be better?

    [I am guessing...is it because not everyone entering the cafeteria will graduate this year? And a better samling technique may be a simple random sample or systematic sample of all final year students? Am I right?]
    I agree with your answer.

    2) Classify the sampling method used in the following scenario:
    The province randomly chooses 25 public schools to participate in a new fundraising initiative.


    [Is it a simple random sample or a cluster sample? The answer in my book says cluster, but I don't understand why isn't this a simple random sample instead?]
    If you look at the definition of cluster sample it should beocme clear that that's what you have here.

    3) A survey uses a cluster sample of Vancouver (a city in Canada) residents to determine public opinion on whether the provincial government should increase funding for the public transit.

    [What type of bias is this? Can somebody please explain? I don't understand...]
    Hint: Vancouver is only one city in the entire province of British Columbia.


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