Finding P-Values using the t-distribution

Finding P-Values using the t-distribution

Here is an example showing the three methods that you can use to find the P-Value when using the t-distribution.

Example: Find the P-Value for a left-tailed test with n=27 and test statistic t = -1.500

Remember that the P-Value is the probability of getting a test statistic that is at least as extreme as the one representing the sample data, assuming that the null hypothesis is true. So, in this case, we want to find the P(t < - 1.500) with deg of freedom = n-1 = 26.

Solution: You have a choice of using either

1) the t-table and find a range of values for the P-Value 2) the T83 PRGM 3) the tcdf DISTR

1) To use the t-table, you need to look at the row for degrees of freedom = df = 26 and find the values for which the absolute value of the test statistic = -1.500 = 1.500 lies in between...notice that the two value are 1.706 and 1.315 ... now look up at the top of the table for "Area in One Tail" and you will notice that these two values correspond with .05 and .10 ...so this tells you that since -1.706 ................
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