Statistical tests are mathematical methods used to determine if there is a significant difference between groups or if a relationship exists between variables. They help researchers analyze data and make informed decisions based on evidence. Common types of statistical tests include t-tests, chi-square tests, and ANOVA. These tests typically involve formulating a null hypothesis, which assumes no effect or difference, and an alternative hypothesis, which suggests otherwise. By calculating a test statistic and comparing it to a critical value, researchers can decide whether to reject the null hypothesis, thus providing insights into their data.