Hypothesis (significance tests: test claims about a population parameter. Test if the mean of the population is a specified value. Test for the difference between two values: tests are based on the sampling distribution, z-scores. We cannot test the alternative hypothesis directly. Instead, we look for evidence against the null hypothesis. If we find significant evidence against the null hypothesis, we can reject it in favour of the alternative hypothesis. Example: assume that someone tells you that the average iq of university students is 113, you want to know whether the average ig at guelph is different from 113, randomly select 100 students. Tools: mean iq of all university students = 113, mean iq from our sample at guelph = 117, assume that the population standard deviation is 13. 5, sample size= 100. Ha: 113: alternative hypothesis does not specify a direction, calculate the z-score by plugging values into the formula.