Hypothesis testing It provides an approach to making inference about a population on the basis of sample information. Decisions are made under uncertainty. The idea behind hypothesis testing is to develop a statistical tool to minimize the probability of error. The method consists of selecting a sample to check the validity of a conjecture or hypothesis. Null and alternative The maintained hypothesis or conjecture is called Ho. The alternative hypothesis (H1) is a conjecture assumed to be true if Ho is false. Objective The objective of the test is to show evidence against the null. The typical analogy is when evidence is presented against a defendant, the null is that the defendant is inocent. Elements of a test of hypothesis 1. Null Ho 2. Alternative H1 3. Test statistic 4. Rejection region (or level of significance) 5. Assumptions about population 6. Sample and compute the test statistic 7. Perform the test 8. Conclusion of the test