Stats exam 4
A critical value, zα, denotes the _______.
.z-score with an area of α to its right.
Which of the following is NOT an observation about critical values?
A critical value is the area in the right-tail region of the standard normal curve.
Which of the following groups has terms that can be used interchangeably with the others?
Percentage, Probability, and Proportion
When analyzing polls, which of the following is NOT a consideration?
The sample should be a voluntary response or convenience sample.
What does it mean to say that the confidence interval methods for the mean are robust against departures from normality?
The confidence interval methods for the mean are robust against departures from normality, meaning they work well with distributions that aren't normal, provided that departures from normality are not too extreme.
A newspaper provided a "snapshot" illustrating poll results from 1910 professionals who interview job applicants. The illustration showed that 26% of them said the biggest interview turnoff is that the applicant did not make an effort to learn about the job or the company. The margin of error was given as ±3 percentage points. What important feature of the poll was omitted?
The confidence level
Which of the following is NOT a requirement for constructing a confidence interval for estimating a population mean with σ known?
The confidence level is 95%.
Which of the following is NOT a property of the Student t distribution?
The standard deviation of the Student t distribution is s=1.
A magazine provided results from a poll of 1500 adults who were asked to identify their favorite pie. Among the 1500 respondents, 14% chose chocolate pie, and the margin of error was given as ±3 percentage points. Describe what is meant by the statement that "the margin of error was given as ±3 percentage points."
The statement indicates that the interval 14%±3% is likely to contain the true population percentage of people that prefer chocolate pie.
Which of the following is NOT a requirement for constructing a confidence interval for estimating the population proportion?
The trials are done without replacement.
Which concept below is NOT a main idea of estimating a population proportion?
Using a sample statistic to estimate the population proportion is utilizing descriptive statistics.
Which of the following would be a correct interpretation of a 99% confidence interval such as 4.1<μ<5.6?
We are 99% confident that the interval from 4.1 to 5.6 actually does contain the true value of μ.
Which of the following would be a correct interpretation of a 99% confidence interval such as 4.1<μ<5.6?
We are 99% confident that the interval from 4.1 to 5.6 actually does contain the true value of μ.
Refer to the accompanying data display that results from a sample of airport data speeds in Mbps. The results in the screen display are based on a 95% confidence level. Write a statement that correctly interprets the confidence interval. TInterval (13.046,22.15) x=17.598 Sx=16.01712719 n=50
We have 95% confidence that the limits of 13.05 Mbps and 22.15 Mbps contain the true value of the mean of the population of all data speeds at the airports.
A food safety guideline is that the mercury in fish should be below 1 part per million (ppm). Listed below are the amounts of mercury (ppm) found in tuna sushi sampled at different stores in a major city. Construct a 98% confidence interval estimate of the mean amount of mercury in the population. Does it appear that there is too much mercury in tuna sushi?
Yes, because it is possible that the mean is greater than 1 ppm. Also, at least one of the sample values exceeds 1 ppm, so at least some of the fish have too much mercury.
The number of _______ for a collection of sample data is the number of sample values that can vary after certain restrictions have been imposed on all data values.
degrees of freedom
A _______ is a single value used to approximate a population parameter.
point estimate
The _______ is the best point estimate of the population mean.
sample mean
