Statistics CH 7

"Estimation" refers to a class of... robust statistics. descriptive statistics. inferential statistics. sample statistics.

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. sample value point estimate nominal estimate inferential statistic

point estimate

If you can use only one number to estimate a population parameter, then the best value is a... probability value. confidence interval. null hypothesis. point estimate.

point estimate.

As the mean for a distribution increases, then the width of the corresponding confidence interval will... become wider. become more biased. stay the same. become narrower.

stay the same.

As the mean for a sample becomes greater, the width of the corresponding confidence interval will... stay the same. become undefined. increase. decrease.

stay the same.

A point estimate for the population mean is based on... the sample mean. the sample size. the sampling distribution of means. normally distributed data only.

the sample mean.

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.) (119.00, 123.00) (118.44, 123.56) (120.68, 121.32) (119.72, 122.28)

(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) (181.59, 184.41) (179.71, 186.29) (180.00, 186.00)

(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.) (54.22, 55.78) (51.08, 58.92) (53.04, 56.96) (53.00, 57.00)

(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.) 60 (39.67, 83.03) (59.53, 60.47) (56.71, 63.29)

(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.) (67.00, 69.00) (48.00, 88.00) (67.92, 68.08) (66.36, 69.64)

(66.36, 69.64)

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? 86-136 106-114 Cannot be calculated without additional information 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? Cannot be calculated without additional information 80 78-82 70-90

80

Which is generally more accurate (in the statistical sense): a point estimate or a confidence interval? - A point estimate - They are the same - Cannot be determined without additional information - A confidence interval

A confidence interval

Which is generally more precise (in the statistical sense): a point estimate or a confidence interval? A confidence interval Cannot be determined without additional information A point estimate They are the same

A point estimate

Which is more precise (in the statistical sense): a point estimate or a confidence interval? A confidence interval Cannot be determined without additional information A point estimate They are the same

A point estimate

When we talk about "estimation" in statistics, what is it that is being estimated? The degree of sampling bias A population parameter A sampling distribution The values for missing data

A population parameter

For which measures is it possible to compute a confidence interval? - Only measures with normally distributed scores - Only unbiased measures - Any population parameter - Only the population mean

Any population parameter

How is a confidence interval affected when the sample size increases? It increasingly resembles a normal distribution It becomes less biased It becomes narrower It becomes wider

It becomes narrower

How is a confidence interval affected when the sample standard deviation decreases? It becomes narrower It increasingly resembles a normal distribution It becomes wider It becomes less biased

It becomes narrower

How is a point estimate affected when the sample size increases? It becomes higher It becomes lower It does not change It becomes narrower

It does not change

How is the point estimate affected when the sample standard deviation increases? It becomes lower It becomes higher It does not change It becomes narrower

It does not change

What is one important difference between a point estimate and a confidence interval? - The point estimate is based on sample data instead of population data - The confidence interval is used only for unbiased statistics instead of biased ones - The confidence interval gives two numbers instead of one - The point estimate cannot be used for inferring population values

The confidence interval gives two numbers instead of one

The sample mean is ________ and a confidence interval for the mean is _______. - a biased measure; an unbiased measure - for n < 100 only; for n > 100 only - a sample value; also a sample value - a descriptive statistic; an inferential statistic

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. be more difficult to calculate. be less biased. become wider.

become narrower.

As the standard deviation for a distribution increases, then the corresponding confidence interval will... stay the same. become wider. become narrower. become more biased.

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. be less accurate. be more difficult to calculate. become narrower.

become wider.

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 precise confidence interval? Sample B They will be the same Cannot answer without additional information Sample A

Sample A

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 - They will be the same - Cannot answer without additional information - Sample A

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? They are the same Sample A Cannot be determined without additional information Sample B

Sample B