Question 1
0 / 5 pts
Which of the following would be a good example of a test of the difference of two matched means?
A veterinarian switches from one brand of dog muzzle to another, and sees if the average heart rate of her patients is different between the two brands (each dog is randomly selected to wear one kind of muzzle or another).
You Answered
A veterinarian switches from one brand of dog muzzle to another, and checks to see if the fraction of dogs who become agitated is different.
Correct Answer
A veterinarian switches from one brand of dog muzzle to another, and sees if the average heart rate of her patients is different between the two brands (each dog wears each kind of muzzle).
A veterinarian switches from one brand of dog muzzle to another, and checks whether the breed of dog predicts whether or not the dog is likely to become more agitated, less agitated, or show no change.
A veterinarian switches from one brand of muzzle to another, and checks whether the proportion of breeds who react unfavorably to the change matches the expected proportion of breeds in her practice.
Question 2
0 / 5 pts
Which of the following would be a good example of a test of the difference of two proportions?
You Answered
A university compares a random sample of honor roll students’ SAT scores with a random sample of SAT scores of students considered “at risk” to see if there is a difference between the scores of each group.
Correct Answer
A university compares a random sample of honor roll students to a random sample of students considered “at risk” to see if there is a difference between the fraction in each group who chose to submit ACT scores to the university.
A university looks at a group of randomly selected students’’ grades before and after their participation in a new “study skills” intervention program to see if there is a difference in scores resulting from the program.
A university considers whether the high school attended by in-state students is related to whether the student graduates within four years, more than four but within six years, or doesn’t graduate within six years.
A university checks whether the fraction of its students graduating within four years, more than four but within six years, or not graduating within six years matches with the national averages in each category.
Question 3
0 / 5 pts
Which of the following would be a good example of a test of the difference of two independent means?
Correct Answer
A university compares a random sample of honor roll students’ SAT scores with a random sample of SAT scores of students considered “at risk” to see if there is a difference between the scores of each group.
A university compares a random sample of honor roll students to a random sample of students considered “at risk” to see if there is a difference between the fraction in each group who chose to submit ACT scores to the university.
A university looks at a group of randomly selected students’ grades before and after their participation in a new “study skills” intervention program to see if there is a difference in scores resulting from the program.
A university considers whether the high school attended by in-state students is related to whether the student graduates within four years, more than four but within six years, or doesn’t graduate within six years.
You Answered
A university checks whether the fraction of its students graduating within four years, more than four but within six years, or not graduating within six years matches with the national averages in each category.
Question 4
0 / 5 pts
Which of the following would be a good example of a chi-squared goodness of fit test?
A university compares a random sample of honor roll students’ SAT scores with a random sample of SAT scores of students considered “at risk” to see if there is a difference between the scores of each group.
You Answered
A university compares a random sample of honor roll students to a random sample of students considered “at risk” to see if there is a difference between the fraction in each group who chose to submit ACT scores to the university.
A university looks at a group of randomly selected students’’ grades before and after their participation in a new “study skills” intervention program to see if there is a difference in scores resulting from the program.
A university considers whether the high school attended by in-state students is related to whether the student graduates within four years, more than four but within six years, or doesn’t graduate within six years.
Correct Answer
A university checks whether the fraction of its students graduating within four years, more than four but within six years, or not graduating within six years matches with the national averages in each category.
Question 5
5 / 5 pts
Which of the following would be a good example of a chi-squared test of independence?
A university compares a random sample of honor roll students’ SAT scores with a random sample of SAT scores of students considered “at risk” to see if there is a difference between the scores of each group.
A university compares a random sample of honor roll students to a random sample of students considered “at risk” to see if there is a difference between the fraction in each group who chose to submit ACT scores to the university.
A university looks at a group of randomly selected students’ grades before and after their participation in a new “study skills” intervention program to see if there is a difference in scores resulting from the program.
Correct!
A university considers whether the high school attended by in-state students is related to whether the student graduates within four years, more than four but within six years, or doesn’t graduate within six years.
A university checks whether the fraction of its students graduating within four years, more than four but within six years, or not graduating within six years matches with the national averages in each category.
Question 6
5 / 5 pts
A professor is curious whether online students score higher or lower on a certain test.
A random sample of online students earn the following scores:
| 85 | 95 | 87 | 77 | 68 | 75 | 80 | 62 | 97 | 88 |
A random sample of in-person students earn the following scores:
| 77 | 60 | 69 | 73 | 65 | 88 | 94 | 75 | 81 |
Calculate the test statistic, rounding to the nearest 0.01.
Correct!
Correct Answers
1.11 (with margin: 0.1)
-1.11 (with margin: 0.1)
Question 7
0 / 5 pts
Perform a test for the difference of two populations
A consumer group surveys clients of two different investment firms to see if their customers have different average levels of satisfaction. Thirty clients of the first firm respond to the survey, reporting an average satisfaction of 5.9 on a 7-point scale, with a sample standard deviation of 0.4; the thirty-five respondents from the second firm report an average satisfaction of 5.2 with a standard deviation of 0.5. Calculate the test statistic for this case (to the nearest 0.1).
You Answered
Correct Answers
6.27 (with margin: 0.1)
-6.27 (with margin: 0.1)
Question 8
5 / 5 pts
Interpret a test for a test of independence.
A wireless company finds a p-value of 0.008 against the null hypothesis that demographic category has no effect on what type of wireless plan is preferred. Interpret this result using a traditional 0.05 level of significance.
Correct!
Because the p—value is low, we have evidence that demographic category affects plan preference.
Because the p—value is high, we have evidence that demographic category affects plan preference.
Because the p—value is low, we do not have evidence that demographic category affects plan preference.
Because the p—value is high, we do not have evidence that demographic category affects plan preference.
Question 9
5 / 5 pts
Differentiate matched and unmatched tests
Which of the following is true about the hypothesis test difference of two matched samples?
Degrees of freedom cannot be calculated by hand for the t test
Degrees of Freedom are Unnecessary, even for the t test
Correct!
Degrees of Freedom for the t-test are easier to calculate
It’s always a z test and never a t test.
Question 10
5 / 5 pts
Perform a chi squared goodness of fit test
A web advertiser wants to know if four different advertisements are equally likely to be clicked on. Treating a group of 40 clicks as a random sample, she observes 11 from ad A, 8 from ad B, 11 from ad C and 10 from ad D. What is the chi-squared value for this case (round to the nearest 0.1)?
Correct!
Correct Answers
0.6 (with margin: 0.01)
Question 11
5 / 5 pts
Perform a chi squared test of independence
In the table below, a surveyor want to know if the demographic category of the respondent (A, B, or C) is related to whether they answered “Yes” or “No” on the survey. Calculate the chi-squared test of independence for this data and find the test statistic (round to the nearest 0.01).
| Yes | No | |
| A | 12 | 7 |
| B | 15 | 10 |
| C | 18 | 15 |
Correct!
Correct Answers
0.405 (with margin: 0.01)
Question 12
5 / 5 pts
Find the degrees of freedom for a chi-squared test
A job placement firm would like to know whether the five categorical variables they have for a certain group of applicants can be used to predict which of five different outcomes they will have in their job search. If they test this using a chi-squared test of independence, how many degrees of freedom will they have?
Correct!
Correct Answers
16.0 (with margin: 0.0)
Question 13
5 / 5 pts
Interpret p-value
A colleague surveys several clients about their experiences with two products and finds a p-value of 0.04 against the null hypothesis that the products are equally effective. What does this mean?
Correct!
If there really is no difference between the products, we’d only expect this much of a difference in the survey results 4% of the time.
If there really is a difference between the products, we’d only expect this much of a difference in the survey results 4% of the time.
There is a 96% chance there is really a difference between the products.
There is a 4% chance there is really a difference between the products.
Quiz Score: 40 out of 65
