Question

6.) P-values: First, and most important, what is a p-value? A p-value is the probability of getting the sample results IF the null hypothesis is true. This is the definition of a p-value. VERY IMPORTANT: A p-value is NOT the probability of the null hypothesis being true. If you remember only one statistical thing from this exam, please remember this idea regarding p-values. Also, look into the following regarding p-values:

a.) How are they calculated?

b.) How are they used to draw conclusions in hypothesis testing?

Answer 1

a)

P-values are calculated by finding the probability of the observed, or more extreme test statistic results when the null hypothesis (H0) of a study question is true.

For example if test statistic z = 1.96 based on the observed data under the assumption that the null hypothesis is true.

Then, p-value = P(z > 1.96) = 0.025

b)

P-values are compared with the significance level of the hypothesis test.

If p-value is less than significance level, we reject null hypothesis H0 and conclude that the results are significant to claim that alternative hypothesis is true.

If p-value is greater than significance level, we fail to reject null hypothesis H0 and conclude that the results are not significant to claim that alternative hypothesis is true.