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Unit 2:Probability and Probability Distributions

Unit Outline

Chapter 5- Introduction to Probability

Chapter 6- Discrete Random Variables

Chapter 7- Continuous Random Variables

Recall that statistics is a process. So far, we have discussed the first three steps in that process. Namely, we can identify questions and relevant populations, collect the data, and organize and summarize the data. The final step is to use the data to make an inference, or a judgement about the population. See figure 5.1.

The four steps in the process of statistics: identify the question and population, collect the data, organize and summarize the information, and make an inference if appropriate. A brace over the first three steps is labeled "Unit 1: Chapters 1, 2, 3, and 4." The arrow between organizing the information and making an inference is circled and labeled "You are here! Unit 2: Chapters 5, 6 and 7." An arrow labeled "Unit 3" points to the final step, making an inference.Unit 1: Chapters 1, 2, 3, and 4YOU ARE HERE!Unit 2: Chapters 5, 6 and 7Unit 3

Figure 5.1: The process of statistics

Unit 2 consists of the study of probability, which is needed to move from descriptive statistics (step 3) to inference (step 4) in the process of statistics. We need to know when the data we collect allow us to reach firm conclusions. How certain can we be that our results reflect the truth? Can we be 99% certain in our results? How about 95%? Can we determine when the results are unreliable? How much evidence in the form of data do we need to be very confident in our conclusions? These questions will be investigated in Unit 3.

This unit begins with basic probability in chapter 5 and continues through the probability needed to study discrete quantitative variables in chapter 6 and continuous quantitative variables and sampling distributions in chapter 7. After covering probability in Unit 2 we will return to the process of statistics and study inference in Unit 3.

So, on to probability!