Explain the difference between expected and observed outcomes. Identify the two possible explanations for differences between observed and expected outcomes and explain how probability is used to determine which of these potential explanations is the true explanation. Define the null hypothesis and the alternative hypothesis and write each out in both words and symbols. Summarize the logic behind the assumption that the null is true. Define Type I and Type II errors and explain the trade-off between them. List the four types of bivariate inferential tests, and identify the correct one to use for any given independent variable and dependent variable combination depending on level of measurement.