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18 Cards in this Set
- Front
- Back
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What is the z for a 90% confidence interval?
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1.645
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What is the Z for a 95% confidence interval?
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1.96
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What is the Z for a 99% confidence interval?
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2.575
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What is a confidence interval?
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An interval of numbers within which we expect the true value of the parameter to be contained.
Example- 90%, 95%, 98%, 99% |
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Confidence Coefficient
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The proportion of times that a confidence interval encloses the true value of the population parameter if the confidence interval procedure is used repeatedly a large number of times.
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What is the FPC?
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Finite Population Correction Factor
Square root of: N-n/N-1 |
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When can you disregard the FPC?
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If the sample size is less than or equal to 5% of the population size.
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What is the Standard Error of the Mean?
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The standard deviation of (x̄)
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Is the sample mean a biased or unbiased estimator of the population mean?
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It is unbiased.
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Explain what it means to be unbiased?
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If a sample statistic has a sampling distribution with a mean equal to the population parameter the statistic is to estimate, the statistic is said to be an unbiased estimator. Otherwise it is a biased estimator.
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What is a sampling distribution?
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A statistic calculated from samples of n measurements is the probability distribution of the statistic.
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What is a point estimator?
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A point estimator of a parameter is a rule that tells how to use the sample data to calculate a single value that can be used as an estimate of the population paramter.
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Systematic Sampling?
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Useful when you have a large population. Randomly choose a starting point, and then systematically choose every kth value.
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What are the nonprobability sampling techniques?
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1. Convenience Sampling
& 2. Judgment Sampling |
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Define Convenience Sampling.
What are the advantages and disadvantages? |
A sample chosen for convenience. The advantage is that the sample is easy to obtain, but it is impossible to evaluate if the sample provides a "good" estimate of population characteristics.
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Define Judgment Sampling.
What are the advantages and disadvantages? |
A researcher selects a sample they think is representative of the population. The advantage is that the sample is easy to obtain. The disadvantages are that you cannot tell if the sample is "good", and there could be a tendency for the sample to be biased.
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Define Cluster Sampling
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Occurs when the population is divided into two or more groups of sampling units, called clusters. A simple random sample of clusters is taken.
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Advantages of cluster sampling?
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1. Easier to construct a list of clusters than a list of individual elements in a population.
2. Elements in a cluster are often geographically close to one another, making sampling cheaper and less labor intensive. |
