Chapter 9 summary

Chapter 9 summary - Chapter 9 We can produce data intended...

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Chapter 9 We can produce data intended to answer specific questions by observational studies or experiments . Sample surveys that select a part of a population of interest to represent the whole are one type of observational study. Experiments , unlike observational studies , actively impose some treatment on the subjects of the experiment . Variables are confounded when their effects on a response can’t be distinguished from each other. Observational studies and uncontrolled experiments often fail to show that changes in an explanatory variable actually cause changes in a response variable because the explanatory variable is confounded with lurking variables . In an experiment , we impose one or more treatments on individuals , often called subjects . Each treatment is a combination of values of the explanatory variables , which we call factors . The design of an experiment describes the choice of treatments and the manner in which the subjects are assigned to the treatments
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Chapter 9 summary - Chapter 9 We can produce data intended...

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