n_0517 - Chapter 3: Producing Data Chapter 3 1 How to...

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Chapter 3 1 Chapter 3: Producing Data
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Chapter 3 2 How to collect data that can be used to answer questions about large groups or populations? Collecting data of large population is often Expensive Time consuming Impossible If we carefully design the production of data on a smaller sale, we can use our data to draw conclusions about a wider setting.
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Chapter 3 3 Population vs. Sample The population is the entire group of individuals about which we want information. A sample is a part of the population from which we actually collect information, used to draw conclusion about the whole. Sample Design is the method used to choose the sample from the population.
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Chapter 3 4 Sample design Out of necessity we take a sample from the population. The sample must be designed so that it mirrors the population as much as possible. Information from the sample can then be used to make reasonable conclusions about the population.
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Chapter 3 5 Observational Study Definition: An observational study observes individual and measures variables of interest but does not attempt to influence the responses. Example: Sample surveys Collecting data from public records Election polls Observational studies of the effect of one variable on another often fail because the explanatory variable is mixed up with lurking variable.
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Chapter 3 6 Experiment Definition: An experiment deliberately imposes some treatment on individuals to observe their responses. Example: Study whether the cell phone radiation injury people’s brain? Expose one group of mice to cell phone radiation regularly The other similar group of mice are forbidden to the radiation When our goal is to understand cause and effect, experiments are the only source of fully convincing data.
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Chapter 3 7 Confounding Variables
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This note was uploaded on 02/27/2008 for the course BCOR 1020 taught by Professor Liang,fang during the Summer '07 term at Colorado.

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n_0517 - Chapter 3: Producing Data Chapter 3 1 How to...

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