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# ch1_sol - A sample is simply a subset of a larger...

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Chapter 1 Solutions to Even Problems 1.2 “Descriptive statistics” refers to a set of numerical or graphical tools used to summarize a set of data. The data can be from a population or from a sample. “Inferential statistics” refers to a set of tools/procedures used to make statements/generalizations about a large group of people/objects based on data collected on a subset (sample) from that group. These methods often use descriptive statistics to summarize the data from the sample, but when the summaries are treated as if they summarize the larger group, we call that an “inference.” 1.6 Quantitative (numeric) data are data values that can be naturally located on the number line. Qualitative (categorical) data are data values that cannot be naturally located on the number line; they are simply labels for groups or classes. 1.8 The difference between samples and populations is similar to the ideas of sets and subsets.
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Unformatted text preview: A sample is simply a subset of a larger population. For example, the set of students in your statistics class is a sample from the population of all students taking statistics in the world. 1.10 When we use summaries of sample data as if they are actually summaries of a population, we have made a statistical inference which will almost certainly be incorrect; we cannot expect our summary of the sample data to have the same value as the summary of the population data. Given that there will be some “error” in making the inference, we need to know how close our inference comes to being correct. Without a measure of the inference’s reliability (“margin of error” is one measure of reliability), we have no way of knowing how close our inference is to the truth....
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