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    Determine if coin is fair




    I am using a chi-squared test to determine if a coin is fair. Here are my results.

    tosses: 10
    heads: 6

    x: 1.92
    Degrees of Freedom: 1

    Result: 16.6%

    1) Does this mean that the probability of 6 heads in 10 tosses is less than 16.6%?

    2) Why doesn't this test take the number of tosses into account? What is the degree of confidence?

    3) Bottom line is that I want to know if the coin is fair. How many tosses do I need and what is the result that I'm looking for?

    Thanks.

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    You can use a chi-square goodness-of-fit test. The "model" distribution would be 5 heads and 5 tails in 10 tosses, and you're evaluating a situation of 6 heads and 4 tails to see if it's "very unusual" (or statistically significant).

    Look at this post in the Examples section, which is similar to your problem (scroll down to chi-square test of independence):
    http://www.talkstats.com/showthread.php?t=204

  3. #3
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    yes, i have used a chi-squared test. my question is on the interpretation of the result. can you answer the three questions from my previous post? thanks.

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