BESC 3010 CH7
How is a confidence interval affected when the sample size increases?
It becomes narrower
How is a confidence interval affected when the sample standard deviation decreases?
It becomes narrower
How is the point estimate affected when the sample standard deviation increases?
It does not change
How is a point estimate affected when the sample size increases?
It does not change.
The sample mean is ________ and a confidence interval for the mean is _______.
a descriptive statistic; an inferential statistic
When the range of confidence for a confidence interval becomes lower - from 90% to 80%, for example - then the confidence interval will...
become narrower
"Estimation" refers to a class of...
inferential statistics.
A confidence interval specifies a range of values for a parameter estimate, whereas a(n) _____ specifies just a single value for that parameter.
point estimate
If you can use only one number to estimate a population parameter, then the best value is a...
point estimate.
As the mean for a distribution increases, then the width of the corresponding confidence interval will...
stay the same
Imagine a sample with n = 64 and a mean of 121 that comes from a population with a standard deviation of 16. Based on these data, what would be the 80% confidence interval for the population mean? (Use z-scores of ±1.28 for the 80% confidence level.)
(118.44, 123.56)
Imagine a sample with n = 49 and a mean of 183 that comes from a population with a standard deviation of 21. Based on these data, what would be the 99.9% confidence interval for the population mean? (Use z-scores of ±3.29 for the 99.9% confidence level.)
(173.13, 192.87)
Imagine a sample with n = 25 and a mean of 55 that comes from a population with a standard deviation of 10. Based on these data, what would be the 95% confidence interval for the population mean? (Use z-scores of ±1.96 for the 95% confidence level.)
(51.08, 58.92)
Imagine a sample with n = 49 and a mean of 60 that comes from a population with a standard deviation of 7. Based on these data, what would be the 99.9% confidence interval for the population mean? (Use z-score of \pm 3.29 for the 99.9% confidence level.)
(56.71, 63.29)
Imagine a sample with n = 400 and a mean of 68 that comes from a population with a standard deviation of 20. Based on these data, what would be the 90% confidence interval for the population mean? (Use z-scores of ±1.64 for the 90% confidence level.)
(66.36, 69.64)
As the standard deviation for a distribution increases, then the corresponding confidence interval will...
Become wider
When the range of confidence for a confidence interval becomes higher - from 80% to 99%, for example - then the confidence interval will...
Become wider
What is the point estimate for the population mean if the population standard deviation is 24, the sample size is 36, and the sample mean is 110?
110
What is the point estimate for the population mean if the population standard deviation is 10, the sample size is 100, and the sample mean is 80?
80
Which is generally more accurate (in the statistical sense): a point estimate or a confidence interval?
A confidence interval
Which is generally more precise (in the statistical sense): a point estimate or a confidence interval?
A point estimate
Which is more precise (in the statistical sense): a point estimate or a confidence interval?
A point estimate
When we talk about "estimation" in statistics, what is it that is being estimated?
A population parameter
For which measures is it possible to compute a confidence interval?
Any population parameter
Imagine that samples - Sample A with n = 20 and Sample B with n = 200 - are drawn from the same population and confidence intervals are computed for the same variables, which sample will likely have the more accurate confidence interval?
Sample B
Imagine that two samples - Sample A with n = 20 and Sample B with n = 200 - are drawn from the same population and confidence intervals are computed for the same variables, which sample will have the narrower confidence interval?
Sample B
Imagine two samples that are drawn from the same population and measure the same variables in the same way. Sample A has a larger confidence interval than Sample B does. Which sample likely has the larger n?
Sample B
As the mean for a sample becomes greater, the width of the corresponding confidence interval will...
Stay the same
What is one important difference between a point estimate and a confidence interval?
The confidence interval gives two numbers instead of one
A point estimate for the population mean is based on...
The sample mean