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Math Help - Why use a Z Test or a T Test?

  1. #1
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    Why use a Z Test or a T Test?

    Could someone explain why to me why in some cases you use a Z Test Statistic and in others you use a T Test Statistic?

    Thanks.
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  2. #2
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    Quote Originally Posted by Dogfighters View Post
    Could someone explain why to me why in some cases you use a Z Test Statistic and in others you use a T Test Statistic?

    Thanks.
    I asssume you are looking at sample means of data drawn from a normal disrtribution for small sample size. If the population variance is known the sample means have a normal distribution and you should use the z-statistic, if the population variance is unknown and you estimate it from the sample then you use the t-statistic.


    CB
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