[Solved] What is the role of research in criminal justice policy? P-Value: The p-value is a measure in statistical hypothesis testing representing the probability of obtaining a result at least as extreme as the observed one, assuming the null hypothesis is true. Hypothesized Mean Difference: The presumed difference between the means of two populations or conditions being compared in a statistical hypothesis test. Two-Tail: A term used in statistics referring to the two-tailed test of significance that checks for the possibility of positive or negative differences. Observations: The act of noting and recording something with instruments or the naked eye as part of a scientific or empirical study.