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Math Help - Hypothesis about proportions/P-values check please

  1. #1
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    Hypothesis about proportions/P-values check please

    According to a June 2004 Gallup poll, 28% of Americans “said there have been times in the last year when they haven’t been able to afford medical care.” Is this proportion higher for black Americans than for all Americans? In a random sample of 801 black Americans, 34% reported that there had been times in the last year when they had not been able to afford medical care.
    Test an appropriate hypothesis and state your conclusion. (Make sure to check any necessary conditions and to state a conclusion in the context of the problem.)


    H0: _____p=.28______ HA: ___p>.28__________


    Sample proportion: _____801________


    Standard deviation SD(p0): _________.01586______

    Is your test one-tail right (upper) tail, one-tail left (lower) tail, or two-tail?

    ______uppertail________

    P-value:
    __normalCDF(3.783, 10^9, 0, 1) = .0000775 (not sure at all)

    Explain what your P-value means in this context.

    That it is unlikely to observe a poll of 28% Americans to claim they couldn't afford insurance





    Conclusion:

    We are to reject the null hypothesis since the p-value is so low, and that the proportion for black americans is higher than for all americans


    ?? im really not sure about these answers because of my p-value it seems so funky...












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  2. #2
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    The first thing I would ask, is do you know how to calculate the P-Value by hand?

    We are going to assume that the population proportion is normally distributed, and we use a Z-chart to find our P-Value. If our P-Value is less than our SIGNIFICANCE level, then we reject our null hypothesis; otherwise we fail to reject our null hypothesis.

    Our P-Value is the probability that the sample of blacks we ask, are going to yield us a value of 0.34 by CHANCE. This is why you want a SMALL P-Value, as a P-Value of say - 0.11 is probably not the percent of chance you want (of course this all depends on the parameters of what we are testing).

    That it is unlikely to observe a poll of 28% Americans to claim they couldn't afford insurance
    Remember, the P-Value is not the probability of success/non-success of our null-hypothesis. P-Values are a tough-nut to wrap your head around. Check this link out for a little help.
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