Chapter1_StudyGuide_BPS5_Final

Chapter1_StudyGuide_BPS5_Final - CHAPTER 1 PICTURING...

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1 CHAPTER 1 PICTURING DISTRIBUTIONS WITH GRAPHS O VERVIEW Understanding data is one of the basic goals in statistics. To begin, identify the individuals or objects described, then the variables or characteristics being measured. Once the variables are identified, you need to determine whether they are categorical (the variable puts individuals into one of several groups) or quantitative (the variable takes meaningful numerical values for which arithmetic operations make sense). The guided solution for Exercise 1.1 provides more details on deciding whether a variable is categorical or quantitative. After looking over the data and digesting the story behind it, the next step is to describe the data with graphs. Simple graphs give the overall pattern of the data. Which graphs are appropriate depends on whether or not the data are numerical. Categorical data (nonnumerical data) are graphed in bar charts or pie charts. Quantitative data (numerical data) are graphed in histograms or stemplots. Quantitative data collected over time use a time plot in addition to a histogram or stemplot. When examining graphs, be on the alert for the following: Outliers (unusual values) that do not follow the pattern of the rest of the data • Some sense of a center or typical value of the data • Some sense of how spread out or variable the data are • Some sense of the shape of the overall pattern In time plots, be on the lookout for trends over time. These features are important whether we draw the graphs ourselves or depend on a computer to draw them for us. G UIDED S OLUTIONS Exercise 1.1 KEY CONCEPTS: Individuals and types of variables (a) When identifying the individual or objects described, you need to include sufficient detail so that it is clear which individuals are contained in the data set.
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2 Chapter 1 (b) Recall that the variables are the characteristics of the individuals. Once the variables are identified, you need to determine whether they are categorical (the variable puts individuals into one of several groups) or quantitative (the variable takes meaningful numerical values for which arithmetic operations make sense). Now, list the variables recorded and classify each as categorical or quantitative. Name of variable Type of variable Exercise 1.11 KEY CONCEPTS: Drawing stemplots, splitting stems, and rounding Hints for drawing a stemplot: 1. It is easiest, although not necessary, to first order the data. If the data have been ordered, the leaves on the stems will be in increasing order. Ordered annual health care spending values follow. Health Care Spending
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Chapter1_StudyGuide_BPS5_Final - CHAPTER 1 PICTURING...

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