What is the purpose of a test of hypothesis?
A hypothesis test is a decision-making process that examines a set or sets of data, and on the basis of expectation under null hypotheses, leads to a decision as to whether or not to reject null hypotheses. Because in many circumstances we merely wish to know whether a certain proposition is true or false. The process of hypothesis tests provides a framework for making decisions on an objective basis, by weighing the relative merits of different hypotheses, rather than on a subjective basis by simply looking at the numbers. Different people can form different opinions by looking at data (confounded by chance variation or sampling errors), but a hypothesis test provides a standardized decision-making process that will be consistent for all people