In statistical tests, claims are tested by collecting and analyzing data. Two competing hypotheses are specified in a statistical test. One hypothesis, called the null hypothesis and denoted by H 0, is the statement that observed results are due to pure chance. The word null is used to indicate that there is nothing to the assertion of the hypothesis. The other hypothesis which is called the alternative hypothesis and denoted by H 1 is the statement that there is a real effect. This is the claim we try to establish. The question is whether the data are much more consistent with H 1 than H 0.If so, then H 0 should be rejected. Statistical hypothesis testing enables us to distinguish chance effects from real ones.