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20 Cards in this Set
- Front
- Back
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What is the formula for sampling error?
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x bar - mean
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What are the properties of the Sampling Distribution?
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- Suppose all possible samples of size n are selected from a specified population, and the mean of each sample is computed.
-The mean of all the sample means is exactly equal to the population mean -if the population from which the samples are drawn is normal, the distribution of the sample means is also normally distributed -if the population from which the samples are drawn is not normal, the sampling distribution is approximately normal if the samples are sufficiently large |
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What is a Point Estimate?
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- a point estimate is a single statistic used to estimate a population parameter
-be close to the population parameter |
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What is the Confidence interval?
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- the range of values constructed from sample data so that the parameter occurs within that range at a specified probability
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Alpha is usually what?
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-.01, .05, and .10
- a number between 0 and 1 -Level of Significance |
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What is the level of confidence formula?
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it is 1 - alpha
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What is the relationships to the interval level and confidence level?
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Larger CL Wider Interval
Smaller CL Smaller Interval |
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What is the condition to use the z table or the t distribution?
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- sigma know than z tables
- sigma unknown than t distribution |
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What are the assumptions for z tables?
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-random sample
-normality or large sample -variance or standard deviation of population is known |
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How is lower bound shown?
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negative x bar in front of the formula
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How is upper bound shown?
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postive x bar in from of the z forumula
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What is the T distribution?
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-used when population standard deviation is not known
- big S instead of the sigma |
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What are the assumptions of the T distribution?
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-Random Sampling
-Population is normal or near normal -Variance is Not known |
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What are the characterisitics of a T distribution?
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-Continous Distribution
-Bell Shaped -Symmetrical -Asymptotic -Mean of Zero -< sample size and > Standard Deviation the flatter the distribution |
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What is the difference between t distribution and standard normal distribution?
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- wider tales
- is flatter than normal distribution if the sample size is small |
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What is the T distribution?
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-used when population standard deviation is not known
- big S instead of the sigma |
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What are the assumptions of the T distribution?
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-Random Sampling
-Population is normal or near normal -Variance is Not known |
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What are the characterisitics of a T distribution?
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-Continous Distribution
-Bell Shaped -Symmetrical -Asymptotic -Mean of Zero -< sample size and > Standard Deviation the flatter the distribution |
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What is the difference between t distribution and standard normal distribution?
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- wider tales
- is flatter than normal distribution if the sample size is small |
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What are the assumptions for a Confidence interval for a proportion?
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1. Random Sampling
2. Population follows a binomial distribution 3. n * pi > 10 and n(1-pi)>10 |
