142 4 4-1 Basic Concepts of Probability 4-2 Addition Rule and Multiplication Rule 4-3 Complements, Conditional Probability, and Bayes’ Theorem 4-4 Counting 4-5 Simulations for Hypothesis Tests Probability for Significance PROBABILITY In Chapter 3 we introduced the concepts of significantly low or significantly high sample values. In that chapter, determination of whether values are significantly low or significantly high was based on the range rule of thumb or the use of z scores. Both the range rule of thumb and the use of z scores indicate that a value is significantly low if it is at least two standard deviations below the mean (or z … -2), and a value is significantly high if it is at least two standard deviations above the mean (or z Ú 2). Those criteria are based on the values of the mean and standard deviation, but those statistics could be greatly affected by outliers and the distributions of the data. In many cases (such as correlation), we don’t work with a single mean and standard deviation, so the range rule of thumb can’t be used. We can better identify significant results by using probability values. CHAPTER PROBLEM
RkJQdWJsaXNoZXIy NjM5ODQ=