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Unformatted text preview: information to make conclusions about a larger group of items/individuals than just those in the sample. In most statistical studies, the objective is to use a small group of units (the sample) to make an inference (a decision or judgment) about a larger group (the population). Definitions: Population: The entire group of items/individuals that we want information about, about which inferences are to be made. Sample: The smaller group, the part of the population we actually examine in order to gather information. Variable: The characteristic of the items or individuals that we want to learn about. One way to view these terms is through a Basket Model: Population= basket of balls, 1 ball for each unit in population. X = variable (value of variable is recorded on each ball as small x) 23 Sample = a few balls selected from the basket. Fundamental Rule for Using Data for Inference: Available data can be used to make inferences about a much larger group if the data can be considered to be representative with regard to the question(s) of interest. One principal way to guarantee that sample data represents a larger population is to use a (simple) random sample. Try It! Exercise 5.18 and 5.19 page 177 For each situation explain whether or not the Fundamental Rule holds. 1. Rese...
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This document was uploaded on 02/25/2014 for the course STATS 250 at University of Michigan.
- Summer '10