Exam 10: Introduction to Estimation

Time Spent Playing Computer Games Suppose that the amount of time teenagers spend playing computer games per week is normally distributed with a standard deviation of 1.5 hours.A sample of 100 teenagers is selected at random,and the sample mean computed as 6.5 hours. -{Time Spent Playing Computer Games Narrative} Determine the 95% confidence interval estimate of the population mean if the sample size is changed to 36.

____________________ estimators reflect the effects of larger sample sizes,but ____________________ estimators do not.

The lower limit of the 90% confidence interval for $\mu$ ,where n = 64, $\bar { x }$ = 70,and $\sigma$ = 20,is 65.89.

Time Spent Playing Computer Games Suppose that the amount of time teenagers spend playing computer games per week is normally distributed with a standard deviation of 1.5 hours.A sample of 100 teenagers is selected at random,and the sample mean computed as 6.5 hours. -{Time Spent Playing Computer Games Narrative} Determine the 95% confidence interval estimate of the population mean if the population standard deviation is changed to 2.

In developing an interval estimate for a population mean,a sample of 50 observations was used.The interval estimate was 19.76 $\pm$ 1.32.Had the sample size been 200 instead of 50,the interval estimate would have been:

When determining the sample size necessary for estimating the true population mean,which factor is not of our concern when sampling with replacement?

The bound on the error of estimation is the ____________________ amount of sampling error that we are willing to tolerate.

The sample size needed to estimate the population mean was found to be 865.If the value of the population standard deviation was 75,and the maximum allowable error was 5,then the confidence level used was 95%.

The width of the confidence interval estimate of the population mean $\mu$ is a function of only two quantities: the population standard deviation $\sigma$ and the sample size n.

Define relative efficiency.

If the confidence level is reduced,the confidence interval:

Which of the following is an incorrect statement about a 90% confidence interval?

Time Spent Playing Computer Games Suppose that the amount of time teenagers spend playing computer games per week is normally distributed with a standard deviation of 1.5 hours.A sample of 100 teenagers is selected at random,and the sample mean computed as 6.5 hours. -{Time Spent Playing Computer Games Narrative} Determine and interpret the 99% confidence interval estimate of the population mean.

An unbiased estimator is ____________________ if its variance gets smaller as n gets larger.

The smallest number in a confidence interval is abbreviated by ____________________.

An estimator is said to be consistent if:

The version of the sample variance where you divide by ____________________ gives you an unbiased estimator of the population variance.

Time Spent Playing Computer Games Suppose that the amount of time teenagers spend playing computer games per week is normally distributed with a standard deviation of 1.5 hours.A sample of 100 teenagers is selected at random,and the sample mean computed as 6.5 hours. -{Time Spent Playing Computer Games Narrative} Interpret the 95% confidence interval for this situation.

After constructing a confidence interval estimate for a population mean,you believe that the interval is useless because it is too wide.In order to correct this problem,you need to:

A confidence interval is defined as: