Stats Exam 3

As the size of the sample is increase, the standard deviation of the sampling distribution of the sample mean for a normally distributed population will stay the same

F

The t distribution approaches the standardized normal distribution when the number of agrees of freedom decreases

F

the central limit theorem ensures that the sampling distribution of the sample mean approaches a normal distribution as the sample size increases

T

For sample sizes greater than 30, the sampling distribution of the mean will be approximately normal distributed a. regardless of the shape of the population b. only if the shape of the population is symmetrical c. only if the standard deviation of the samples are known d. only if the population is normally distributed

A

If the expected value of a sample statistic is equal to the parameter it is estimating, then we call that sample statistic a. unbiased b. minimum variance c. biased d. random

A

In the construction of confidence intervals, if all other quantities are unchanged, an increase in the sample size will lead to a ____ interval a. narrower b. wider c. less significant d. biased

A

Sampling distribution of x bar is the a. probability distribution of the sample mean b. probability distribution of the sample proportion c. mean of the variance d. mean of the population

A

The central limit theorem is important in statistics because a. for a large n, it says the population is approximately normal b. for any population, it says the sampling distribution of the sample mean is approximately normal, regardless of the sample size c. for a large n, it says the sampling distribution of the sample mean is approximately normal regardless of the shape of the approximation d. doe any sized sample, it says the sampling distribution of the sample man is approximately normal

A

The standard error of the mean for a sample of 100 is 30. In order to cut the standard error of the mean to 15, we would: a. increase the sample size to 200 b. increase the sample size to 400 c. decrease the sample size to 50 d. decrease the sample to 25

B

The standard error of the population proportion will become larger: a. as population proportion approaches 0 b. as population proportion approaches 0.50 c. as population proportion approaches 1.00 d. as the sample size increases

B

Which of he following is not true about the Students t distribution? a. it has more area in the tails and less in he center than does the normal distribution b. it is used to construct confidence intervals for the population mean when the population standard deviation is known c. it is bell shaped and symmetrical d. As the number of degrees of freedom increases, the t distribution approaches normal distribution

B

The standard error of he mean a. is never larger than the standard deviation of the population b. decreases as the sample size increases c. measures the variability of the mean from sample to sample d. All of the above

D

The standard error of the mean: a. is never larger than the standard deviation of the population b. decreases as the sample size increases c. measures the variability of the mean from sample to sample d. All of the above

D

The t distribution a. assumes the population is normally distributed b. approaches the normal distribution as the sample size increases c. has more area in the tails than does the normal distribution d. All of the above

D

A population parameter is used to estimate a confidence interval

F

A sampling distribution is a distribution for a parameter

F

A point estimate consists of a single sample statistic that is used to estimate the true population parameter

T

The central limit theorem ensures that the sampling distribution of the sample mean approaches a normal distribution as the sample size increases

T

The mean of the sampling distribution of a sample proportion is the population proportion (pi)

T

The sample mean is an unbiased estimator for the population mean

T

if the population distribution is symmetric, the sampling distribution of the mean can be approximated by the normal distribution if the samples contain 15 observations

T