This document discusses one-tailed and two-tailed hypothesis tests. It explains that a one-tailed test looks for an increase or decrease in a parameter, while a two-tailed test looks for any change. If the claim uses words like "increased" or "decreased", it is a one-tailed test, while terms like "change" or "different" indicate a two-tailed test. A one-tailed test has a critical region in one tail, while a two-tailed test has critical regions in both tails. The example given is a one-tailed test comparing civil engineering and B.A. salaries, with the alternative hypothesis that engineering salaries are greater than B.A. salaries.