EXAMPLE 6.21

Information provided by the P-value. Suppose that the test statistic for a two-sided significance test for a population mean is z = 1.95. From Table A we can calculate the P-value. It is

P = 2[1 − P(Z ≤ 1.95)] = 2(1 − 0.9744) = 0.0512

We have failed to meet the standard of evidence for α = 0.05. However, with the information provided by the P-value, we can see that the result just barely missed the standard. If the effect in question is interesting and potentially important, we might want to design another study with a larger sample to investigate it further.