Stats Chapter 8 Interval Estimation
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29 terms
Terms | Definitions |
|---|---|
 The absolute value of the difference between the point estimate and the population parameter it estimates is: | the sampling error |
| When s is used to estimate σ, the margin of error is computed by using | t distribution |
| If we want to provide a 95% confidence interval for the mean of a population, the confidence coefficient is | 0.95 |
| As the number of degrees of freedom for a t distribution increases, the difference between the t distribution and the standard normal distribution | becomes smaller |
| For the interval estimation of μ when σ is known and the sample is large, the proper distribution to use is | the normal distribution |
| An estimate of a population parameter that provides an interval of values believed to contain the value of the parameter is known as the | interval estimate |
| The value added and subtracted from a point estimate in order to develop an interval estimate of the population parameter is known as the | margin of error |
| If an interval estimate is said to be constructed at the 90% confidence level, the confidence coefficient would be | 0.9 |
| Whenever the population standard deviation is unknown and the population has a normal or near-normal distribution, which distribution is used in developing an interval estimation? | t distribution |
| In interval estimation, the t distribution is applicable only when | the sample standard deviation is used to estimate the population standard deviation |
| In developing an interval estimate, if the population standard deviation is unknown | the sample standard deviation can be used |
| In order to use the normal distribution for interval estimation of μ when σ is known and the sample is very small, the population | must have a normal distribution |
| From a population that is not normally distributed and whose standard deviation is not known, a sample of 6 items is selected to develop an interval estimate for the mean of the population (μ). | The sample size must be increased. |
| A sample of 200 elements from a population with a known standard deviation is selected. For an interval estimation of μ, the proper distribution to use is the | normal distribution |
| As the sample size increases, the margin of error | decreases |
| For which of the following values of P is the value of P(1 - P) maximized? a. P = 0.99 b. P = 0.90 c. P = 0.01 d. P = 0.50 | P = 0.50 |
| A 95% confidence interval for a population mean is determined to be 100 to 120. If the confidence coefficient is reduced to 0.90, the interval for μ | becomes narrower |
| Using an α = 0.04 a confidence interval for a population proportion is determined to be 0.65 to 0.75. If the level of significance is decreased, the interval for the population proportion | becomes wider |
| The ability of an interval estimate to contain the value of the population parameter is described by the | confidence level |
| After computing a confidence interval, the user believes the results are meaningless because the width of the interval is too large. Which one of the following is the best recommendation? | Increase the sample size. |
| If we change a 95% confidence interval estimate to a 99% confidence interval estimate, we can expect | the size of the confidence interval to increase |
| In general, higher confidence levels provide | wider confidence intervals |
| An interval estimate is a range of values used to estimate | a population parameter |
| In determining the sample size necessary to estimate a population proportion, which of the following information is not needed? | the mean of the population |
| Whenever using the t distribution for interval estimation (when the sample size is very small), we must assume that | the population is approximately normal |
| A sample of 20 items from a population with an unknown σ is selected in order to develop an interval estimate of μ. Which of the following is not necessary? | The sample must have a normal distribution. |
| When the level of confidence decreases, the margin of error | becomes smaller |
| When constructing a confidence interval for the population mean and the standard deviation of the sample is used, the degrees of freedom for the t distribution equals | n-1 |
| Which of the following best describes the form of the sampling distribution of the sample proportion? | It is approximately normal as long as np 5 and n(1-p) 5. |
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