Statistics 110-002 Chapter 3
Statistics 110-002 Chapter 3 STAT 110 001
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This 2 page Class Notes was uploaded by Megan Ruth Simpson on Thursday September 8, 2016. The Class Notes belongs to STAT 110 001 at University of South Carolina taught by Joshua M. Tebbs in Fall 2016. Since its upload, it has received 4 views. For similar materials see Introduction to Statistical Reasoning in Math at University of South Carolina.
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Date Created: 09/08/16
Statistics 110 Chapter 3 What Do Samples Tell Us? Parameters and Statistics: -Parameter- is a number that that describes a population of individuals. Unless every individual in the population is observed, a population parameter is unknown. -A Statistic- is a number calculated from a sample of individuals. We can calculate the value of a statistic because it is based on the individuals observed in the sample. -The Sample proportion- is an estimate of the population proportion. It is a statistic because we calculated it using the individuals in the sample. Sample proportion is an unbiased estimate Accuracy and Precision: Accuracy- Deals with bias Precision- deals with variability -The Sample Proportion changes from sample to sample, but the values center at the truth about the population. In other words, the sample proportion estimates are “correct on average” this is what it means to be unbiased. -Bias does not depend on sample size (as long as a SRS is used.) -The only difference from changing the sample size is that now the variability is the estimates has changed. -Bias- a consistent, repeated deviation of a sample statistic from a population parameter when we take repeated samples. -Variability- The describes how “spread out” the values of a sample statistic are when we take repeated samples. -The larger the sample size, the smaller the variability. Margin of Error and Confidence Statement: -Margin of Error- a numerical value that quantifies the uncertainty in an estimate. The larger the margin of error, the more uncertainty. -Confidence Statement- a statement about a population parameter. -Confidence statement contains two parts: 1. Margin of error- quantifies how close the sample statistic is to the population parameter. 2. Level of confidence- statement about the population is never completely certain. The level of confidence tells us how confident we are in the statement.
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