Define measures of central tendency (mean, median, mode, range, standard deviation). Define variance. What is the normal curve? What is a z-score? What is theoretical probability? Describe level of significance? Explain sampling error (SE). What is chance variation? What is the difference between a Type I error (alpha) and a Type II error (beta)? Describe some ways to increase power in research. What is the difference between a one-tailed and a two-tailed hypothesis test? Why is knowing the error (Type I and Type II) in a study important?