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Math Help - hp test

  1. #1
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    hp test

    Do not hate me please. It's gonna be over soon.

    Let's see if I understood what we did till now. Let's take this excercice.

    In a random sample of 160 b-schools students, 72 sample members indicated some measure of their agreement with this statement: "scores on a standardized entrance exam are less important for a student's chances to succedeed academically than his high school GPA" Test th enull hypothesis that one half of all b-schools students would agree with this statement against a two sided alternative. Find and interpret the p-value.


    Okay. I found the p value in this way: 72/160= 0.45 so
    (0.45-0.50)/ sqroot(0.5*0.5/160) = -1.265
    I go to the table and find 89.62%. Then I remembe that the alternative is 2 sided, so I do 1-.8962= 1038 and multiply it by 2. So p is 0.2076.

    Now I am unsecure about what to do. Shall I take arbitrary alfa of 5%? Thank you so much for your patiente and help.
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  2. #2
    Grand Panjandrum
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    Quote Originally Posted by 0123 View Post
    Do not hate me please. It's gonna be over soon.

    Let's see if I understood what we did till now. Let's take this excercice.

    In a random sample of 160 b-schools students, 72 sample members indicated some measure of their agreement with this statement: "scores on a standardized entrance exam are less important for a student's chances to succedeed academically than his high school GPA" Test th enull hypothesis that one half of all b-schools students would agree with this statement against a two sided alternative. Find and interpret the p-value.


    Okay. I found the p value in this way: 72/160= 0.45 so
    (0.45-0.50)/ sqroot(0.5*0.5/160) = -1.265
    I go to the table and find 89.62%. Then I remembe that the alternative is 2 sided, so I do 1-.8962= 1038 and multiply it by 2. So p is 0.2076.

    Now I am unsecure about what to do. Shall I take arbitrary alfa of 5%? Thank you so much for your patiente and help.
    Lets assume tha arithmetic is right, then we would expect to see a proportion
    this far from 0.5 about 20% of the time, so we expect that we will not reject
    the null hypothesis (this is because this means that we would expect to see
    a deviation as large as this on about 1 in 5 such surveys)

    Choose alpha to be 5% because you are given no other advice and this
    value is traditional, and as our p-value > 0.05 we do not reject the null
    hypothesis.

    RonL
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  3. #3
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    Quote Originally Posted by CaptainBlack View Post
    Lets assume tha arithmetic is right, then we would expect to see a proportion
    this far from 0.5 about 20% of the time, so we expect that we will not reject
    the null hypothesis (this is because this means that we would expect to see
    a deviation as large as this on about 1 in 5 such surveys)

    RonL
    So you' re telling me that the p value 0.2076 means that we have 20.76% of probability to find a sample value far from 0.5. But how much far? Because of course we are going to get it different, it's a sample..
    I think my problem is that I do not understand what what p value wants to be in its life. My book says "the p value is the smallest significanmce level at which the null hypothesis can be rejected, given the observed sample statistics. " To me it is as clear as thick fog. Might you say it in more basic words? Please, I know I may not be very brilliant(not at all) with statistics, but I am really trying to understand. Thank you very much for all your help Captain.
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  4. #4
    Grand Panjandrum
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    Quote Originally Posted by 0123 View Post
    So you' re telling me that the p value 0.2076 means that we have 20.76% of probability to find a sample value far from 0.5. But how much far? Because of course we are going to get it different, it's a sample..
    As far or further as the value observed

    I think my problem is that I do not understand what what p value wants to be in its life. My book says "the p value is the smallest significanmce level at which the null hypothesis can be rejected, given the observed sample statistics. " To me it is as clear as thick fog. Might you say it in more basic words? Please, I know I may not be very brilliant(not at all) with statistics, but I am really trying to understand. Thank you very much for all your help Captain.
    The dreadfull truth is that this is classical statistics, and though I not
    supposed to tell you I will, it is rubbish, without rational foundation.

    The problem is that this approach to statistics is what is taught to most
    undergraduated for historical reasons, and what you will be examined on.

    When you get through your exams go and read about Bayesian statistics.

    RonL
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  5. #5
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    Quote Originally Posted by CaptainBlack View Post

    When you get through your exams go and read about Bayesian statistics.

    RonL
    You are assuming I will recover from the trauma that this studying of statistics is causing me
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