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When are you allowed to perform a one-sided test? What should you do if you are not sure if it is allowed?
Suppose you have an estimator and would like to test whether or not the population mean value equals 0. What do you need in addition to the estimated value?
Describe the general process of constructing confidence intervals and performing hypothesis tests using the rule of thumb.
Obtain an estimated value and its standard error (either from data or by educated guess) for each of two situations important to your business interests.
Why should you be hesitant to use this sample and the methods of this chapter to compute a confidence interval for the percentage of women?
Find the 95% confidence interval for the population mean quality. Find the 95% prediction interval for the quality of the next measurement.
Find the one-sided 99% confidence interval for the population mean caffeine content of a cup of coffee that claims “at least….”
From a list of the 729 people who went on a cruise, 130 were randomly selected for interview.
Draw a histogram indicating the average and median values, and briefly comment on their relationship. Are they the same? Why or why not?
Find the 95% confidence interval for the amounts that your regular customers spent on your products last month.
Find the one-sided 99% confidence interval that claims that the population percent is no more than some amount.
A nationwide poll claims that the margin of error is no more than 4.3 percentage points for questions asked of half the sample (at the 95% confidence level).
A survey of 21 business intelligence analysts, who had been in their current positions from 10 to 20 years, revealed $90,734 as the average salary.
A survey of eight vice presidents of information technology and information systems, who had been in their current positions for 10 years or less.
During a 1-week experiment, motion was added to in store sales displays at a random sample of your firm’s stores nationwide.
Write a brief paragraph describing how these confidence intervals shed important light on your candidate’s chances.
A market survey has shown that people will spend an average of $2.34 each for your product next year, based on a sample survey of 400 people.
Find the two-sided 95% confidence interval for the percent dissatisfied among all of your customers (i.e, not just those surveyed).
Find the two-sided 95% confidence interval for the mean length of coils in the larger population. Write a brief paragraph explaining its meaning.
As a basis for a brochure describing the speed of a new computer system, you have measured how long it takes the machine to complete a particular benchmark.
Identify the population and the population mean. Why is the population mean important to the management and owners of the proposed mine?
Express your confidence interval in terms of pounds per year, assuming operations continue 365 days/year.
If the distribution of sales prices is heavily skewed, would it be appropriate to construct the usual two-sided 95% confidence interval? Why or why not?
A random sample of 50 recent patient records at a clinic shows that the average billing per visit was $53.01 and the standard deviation was $16.48.
Click-through rates were measured for each of 83 mobile advertising campaigns, and showed an average rate of 2.38%, with a standard error of 0.134%.