Discussion:
Q1: What are Type I and Type II errors? Why do you want to avoid them?
Q2: What is effect size and what does it tell you about your findings?
Q3: What is power of a statistical test and what factors affect it?
Q4: When is it necessary to conduct a t test?
Q5: What are the "degrees of freedom"? Why would you use this term instead of N to calculate a sample variance?