leiyou

 

The correct answer is B

An unbiased estimator is one for which the expected value of the estimator is equal to the parameter you are trying to estimate.

leiyou

 

2、A range of estimated values within which the actual value of a population parameter will lie with a given probability of 1 ? α is a(n):

A) α percent point estimate.

B) (1 ? α) percent confidence interval.

C) α percent confidence interval.

D) (1 ? α) percent cross-sectional point estimate.

leiyou

 

The correct answer is B

A 95% confidence interval for the population mean (α = 5% is the p-value), for example, is a range of estimates within which the actual value of the population mean will lie with a probability of 95%. Point estimates, on the other hand, are single (sample) values used to estimate population parameters. There is no such thing as a α% point estimate or a (1 ? α)% cross-sectional point estimate.

leiyou

 

3、Which of the following statements about sampling and estimation is most accurate?

A) A confidence interval estimate consists of a range of values that bracket the parameter with a specified level of probability, 1 ? β.

B) Time-series data are observations over individual units at a point in time.

C) Cross-sectional data are a set of values of a particular variable in sequential time periods.

D) A point estimate is a single estimate of an unknown population parameter calculated as a sample mean.

leiyou

 

The correct answer is Ｄ　

Time-series data are observations taken at specific and equally-spaced points.

Cross-sectional data are a sample of observations taken at a single point in time.

A confidence interval estimate consists of a range of values that bracket the parameter with a specified level of probability, 1 ? α.

leiyou

 

４、Which of the following would result in a wider confidence interval? A:

A) higher degree of confidence. 

B) higher alpha level. 

C) higher point estimate. 

D) greater level of significance. 

leiyou

 

The correct answer is B

A population includes all members of a specified group. A sample is a portion, or subset of the population of interest.

leiyou

 

2、Which of the following statements about statistical concepts is least accurate?

A) A frequency distribution is a tabular display of data summarized into a relatively small number of intervals.

B) An interval is a set of return values within which an observation falls.

C) A sample contains all members of a specified group, but a population contains only a subset.

D) A parameter is any descriptive measure of a population characteristic.

leiyou

 

The correct answer is C

A population is defined as all members of a specified group, but a sample is a subset of a population.

leiyou

 

AIM 3: Define and distinguish between point estimate, estimation interval.

1、Which of the following statements about sampling and estimation is most accurate?

A) The standard deviation of the distribution of the sample means is the standard error of the residual.

B) The standard error of the sample means when the standard deviation of the population is unknown equals s / √n, where s = sample standard deviation.

C) The standard error of the sample means when the standard deviation of the population is known equals σ / √n, where σ = sample standard deviation adjusted by n ? 1.

D) The probability that a parameter lies within a range of estimated values is given by α.