In: Statistics and Probability
a) To check the normality of a sample, we approached two methods: QQ diagrams and the Shapiro-Wilk test. Please explain the QQ diagrams and the Shapiro-Wilk test and explain why we need such a test?
b) Mr. David, an independent statistician, wishes to test: H0: miu<=20 versus H1: miu>20. If he found the z-score 1.99, can you calculate the value of p using the reduced centered normal distribution table.
c) Explain the concept of sample and explain the difference between a population and a sample.
d) If your data is abnormal, you can use the Mann-Whitney or Wilcoxon tests instead of the t tests. Could you explain the Mann-Whitney and Wilcoxon tests?