Setting Up Hypotheses
This section discusses the logic behind hypothesis testing using concrete examples and explains how to set up null and alternative hypothesis. It explains what Type I and II errors are and how they can occur. Finally, it introduces one-tailed and two-tailed tests and explains which one you should use for testing purposes.
- He would get this score or better if he were just guessing.
If Tommy were guessing blindly, the probability that he would have gotten 16 out of the 20 questions right is.0059. This is NOT the probability that he was guessing blindly. Remember, the probability value is the probability of an outcome given the hypothesis. It is not the probability of the hypothesis given the outcome.
Chance differences will still exist.
- The null hypothesis says that any apparent effect is due to chance, so in this case, the null hypothesis would be that the population correlation was 0.