Choose the correct answer.

1. A scientist wants to test whether participating in support groups will have an effect on the mood of people with depression. Her expectation is that participation will enhance mood. What is the experimental hypothesis?

a. Cannot be determined from the information given

b. Participating in a support group will have no effect on the mood of people with depression.

c. Participating in a support group will improve the mood of people with depression.

d. Participating in a support group will worsen the mood of people with depression.

2. The U.S. Women's Gymnastics team athletic instructor wants to test whether drinking a protein shake will affect the muscle mass of gymnasts. He expects that drinking a protein shake will change the gymnasts' muscle mass. He recruits several gymnasts, measures their muscle mass before and after a month-long protein shake diet, and conducts the appropriate statistical test. A higher score indicates greater muscle mass. Assume that any assumptions needed to perform the statistical test called for have been met. The absolute value of the critical value/s was 2.2 and the test statistic was -2.8. What should he conclude?

a. Drinking a protein shake will increase the gymnasts' muscle mass

b. Cannot be determined from the information given

c. Drinking a protein shake will not change the gymnasts' muscle mass

d. Drinking a protein shake will change the the gymnasts' muscle mass

3. 20 people buy tickets to a charity event at which door prizes will be given away. The organizer gives each attendee a numbered ticket. The organizer then draws a number from a box. Anyone with the matching number wins a prize. If the number on the card does not match that on an attendee's ticket stub, then the organizer puts the card back in the box. The box is vigorously shaken up after each draw. The first two people to walk in the door do not win a door prize. What is the probability that next person who walks through door wins a door prize?

a. 5.6%

b.0%

c.5.0%

d.2.0%

4. A scientist wants to test whether participating in support groups will affect the immune system of people with AIDS. She recruits 6 AIDS patients and measures immune functioning before and after their participation. The table below presents the data she collected. A higher score indicates better immune functioning. Assume that any assumptions needed have been met. What is the value of the test statistic?

Patient	Pre-treatment	Post-treatment
1	35	5
2	50	10
3	30	5
4	55	20
5	40	10
6	30	10
Mean	40	10
SD	10.5	5.5

a. -2.9

b. +/-2.57

c. 2.9

d. -10.4

5. Bill and Sally each sampling distribution of the mean. Both plan to draw samples from the same, normally distributed population of scores. Bill sets his sample size to 10; Sally set her sample size to Which of the two sampling distributions will be more spread out?

a. Sally's sampling distribution

b. Neither. The sampling distributions will not differ

c. Bill's sampling distribution

d. There is not enough information to answer this question

6. A music school director is interested in how the temperature affects how well students learn music. He randomly assigns music students to two groups. In Group A, each student is asked to practice a new piece of music for 10 minutes in a room that is 78 F. In Group B, each student is asked to do the same in a room that is 68 F. After doing so, each student is asked perform the new piece. The accuracy of their performance is rated by a panel of judges; high scores reflect accurate performances. Assume that any assumptions needed have been met.

Group A has a sample size of 20 and a mean rating 15 points.

Group B has a sample size of 20 and a mean of 17 points.

Assume that the samples are distributed normally. The pooled standard error, i.e., estimate of the standard error in the population, is 3.

Use a 2-tailed statistical test.

The critical value/s are +/- 2.1.

What should the musical director conclude?

a. Music students who are accurate at music playing learn quicker in hotter temperatures than cooler temperatures.

b. Sitting in a hot room vs. a cold room has no effect on musical accuracy.

c. A conclusion cannot be made from the information given.

d. Practicing in a hot room vs. a cold room has an effect on the accuracy of a music student's performance.

7. Dr. Lopez wants to test whether participating in support groups will affect the immune system of people with AIDS. Her expectation is that participation will reduce immune functioning. She randomly selects 6 AIDS patients and measures immune functioning before and after their participation. Immune functioning is measured on a ratio scale and is normally distributed. If Dr. Lopez sets alpha to .05, what is/are the critical value/s?

a. +/-1.96

b. -2.02

c. +/-2.57

d. 1.64

8. Dr. Lee conducts a two-tailed, one-sample z-test with an alpha of .05. The randomly-selected sample contains 20 individuals. The scores are on a ratio scale and follow a normal distribution in the population. What are the critical values?

Dr. Lee conducts a two-tailed, one-sample z-test with an alpha of .05. The randomly-selected sample contains 20 individuals. The scores are on a ratio scale and follow a normal distribution in the population. What are the critical values?

a. +/-1.96

b. Cannot be determined from the information given

c. +/-1.64

d. +/-1.50

9. Dr. Jones wants to test whether a finch-like bird in Hawaii is a different species from the finches found in New Zealand. Beak length is used to distinguish finches from other species of birds, so Dr. Jones is going to compare the beak length of a sample of the finch-like birds from Hawaii to the beak length of the population of finches. Suppose that Dr. Jones uses a 2-tailed statistical test. What is the null hypothesis?

a. The beak length of the finch-like birds in Hawaii is less than the beak length of the population of finches

b. The finch-like birds on in Hawaii are finches

c. The finch-like birds in Hawaii are not finches

d. The beak length of the finch-like birds in Hawaii is different from the beak length of the population of finches

10. In this study, professional musicians are assigned to two groups. In Group A, each musician is asked to perform in front of ten friends. In Group B, each musician is asked to perform in front of ten strangers. A panel of judges rate how well each musician performs. What is the experimental question?

a. How well do musicians perform in front of strangers?

b. Does the quality of a musician's performance affect who they perform in front of?

c. Does Group B play better than Group A?

d. Does the relationship of the members of an audience to a musician affect how the musician performs?

11. The basic idea behind hypothesis testing:

a. has very little to do with the type of data you collected.

b. is largely the same across a wide variety of statistical tests.

c. depends quite a bit on the type of test you want to conduct.

d. is important ONLY if you want to compare two populations.

12. Dr. Romanov wants to know whether a Poppy-like flower in Ireland is a different species from the Poppies found on other Islands. Petal number is used to distinguish Poppies from other species of flowers. Dr. Romanov conducts a one-tailed statistical test comparing the number of petals in a sample of Ireland Poppy-like flowers to that in the population of Poppies found on other Islands. The critical value of the test statistic is 2.2; the observed value is -2.5. All the assumptions necessary to conduct the test have been met. What should Dr. Romanov conclude?

a. The Poppy-like flowers in Ireland represent a different species from the Poppies found on other islands.

b.The number of petals on Poppy-like flowers in Ireland is different from Poppies found on other Islands.

c. The Poppy-like flowers in Ireland are Poppies.

d. The number of petals on Poppy-like flowers in Ireland is less than Poppies found on other Islands.

13. Forty subjects are randomly assigned, in equal numbers, to two groups. One group receives an experimental drug for obsessive compulsive disorder (OCD) for one month; the other receives a placebo for the same period. OCD symptom severity is measured afterwards; high scores reflect severe symptoms. Assume that any other assumptions needed to perform the statistical test called for have been met. If the appropriate statistical test is employed with an alpha level of .05 and two-tails, what will be the absolute value of the critical value/s?

a. Cannot be determined from the information given

b. 2.0

c. 3.1

d. 12.5

14. Dr. Jones conducted an experiment. Based on the results of a statistical analysis of the data, she decided to reject the null hypothesis. In reality (that is, in the population), the alternate hypothesis was true. What best describes what took place?

a. She made a Type I error.

b, She made the correct conclusion.

c. She made a Type II error.

d. She made a mistake- probably in her mathematical computations.

15. Dr. Silvio was asked to design a test to detect COVID-19 in elementary school children. He is instructed that infection has a very low probability of serious health consequences whether or not a diagnosis is made, and treatment is delivered. In addition, he is told that false positives have relatively severe consequences because children placed in quarantine will miss school, which is important for their social, emotional, and intellectual development. What Type I error rate should Dr. Silvio select for this test?

a. A Type I error rate higher than .05

b. A Type I error rate of .05

c. A Type I error rate of .10

d.A Type I error rate lower than .05

16. For this study, twenty pairs of twins were recruited. One member of each pair was randomly assigned to one of two groups. The other member of the pair was assigned to the other group. In Group A, each subject is asked to speak to a peer about a problem for 10 minutes. In Group B, each subject is asked to speak an expert about the problem for the same period. Afterwards, the experimenter counts how many solutions to the problem each subject can list in five minutes.

Are Groups A and B independent or related samples?

a. Related

b. Independent

c. Both

d. Neither

17. Darby wants to know if students who attend 4-year colleges in U.S. cities earn more upon graduation, on average, than the average college student in the U.S. She assembles a randomly selected, nationwide sample of 100 graduates of urban 4-year colleges and collects data on their annual first year post-graduation earnings. The mean of their earnings is $50,000; the corresponding SD is $12,500. For all 4-year college students in the U.S., the corresponding mean is $45,000. What is the value of the relevant test statistic?

a. 4

b. 6

c. 8

d. Cannot be determined given the information provided

18. Dr. Fatima is conducting a polygraph test to see if Jared is lying. Jared is a man who is accused of money laundering but says he is innocent. Dr. Fatima wants to be sure the test does not indicate Jared is a lying, if he is actually telling the truth. Dr. Fatima wants to reduce the chances of a Type I, aka alpha, error. What will be the consequences of Dr. Fatima's actions?

a. Dr. Fatima will also reduce the chances that Jared will get away with lying

b. Dr. Fatima will increase the chances that Jared will get away with lying

c. The chances of Jared getting away with lying won't be affected

d. The absolute value of the critical values for alpha will decrease