**For each scenario, you**

Question

**Part A:**

** **

**For each scenario, you**

** must:**

a) Identify the most appropriate statistical test.

b) Identify the independent variable(s) or factor(s).

c) Identify the dependent variable.

d) Identify the scale of measurement for the independent and dependent variables.

**Each answer in Part A counts ½ point for a total of 20 points.**

**Scenario 1 **

Research suggests that exercise can improve cognitive functioning. To test this phenomenon, a researcher selects a sample of 80 students in 4 9th-grade classes and gives them a cognitive functioning test. She has them do a brisk 20-minute walk before each test during a semester. At the end of the semester, the researcher re-administers the cognitive test. The researcher compares the scores before treatment with the scores after treatment to see if there is any change in cognitive function.

**Solution **

a)

b)

c)

d)

**Scenario 2 **

Childhood participation in sports, cuural groups, and youth programs appears to be related to improved self-esteem for adolescents. In a representative study, a researcher compares scores on a self-esteem questionnaire for a sample of 100 adolescents with a history of group participation and a separate sample of 100 who have no history of group participation.

**Solution **

a)

b)

c)

d)

**Scenario 3 **

A researcher investigated different combinations of temperature and humidity to examine how heat affects performance in split-second decision-making skills for college football players. The researcher compared three temperature conditions (70°, 80°, and 90°) with a high humidity and a low humidity condition for each temperature. A separate group of participants was tested in each of the 6 different conditions, and for each participant, the researcher recorded the number of errors made on a decision-making as to the next move on the football field in response to a play.

**Solution **

a)

b)

c)

d)

**Scenario 4 **

A statistics instructor thinks that doing homework improves scores on statistics exams. To test this hypothesis, she randomly assigns students to 2 groups. One group is required to work on the homework until all problems are correct, while homework is optional for the second group. At the end of the semester, exam grades are compared between the 2 groups.

**Solution **

a)

b)

c)

d)

**Scenario 5 **

Intrigued by the statistic professor’s resus, another statistics instructor wonders if it is necessary to complete the entire homework assignment until it is correct or whether just making a significant attempt was sufficient. He randomly assigns students to 3 groups: a homework optional group, a must answer each question group, and a must get all questions correct group.

**Solution **

a)

b)

c)

d)

**Scenario 6 **

Researchers were interested in the effect of grouping on reading scores for male and female 3rd grade students in an after-school reading remediation intervention. Students were assigned to 1 of 3 reading groups: whole-class, small group, and one-on-one.

**Solution **

a)

b)

c)

d)

**Scenario 7 **

A chemistry professor thinks that this year’s freshman class seems to be smarter than previous classes. To test this, he administers an IQ test to a sample of 75 freshmen and computes the mean (M=116.4) and standard deviation (s=14) of their scores. College records indicate that the mean IQ across previous years was 111.2.

**Solution**

a)

b)

c)

d)

**Scenario 8 **

A study is conducted to determine how sunlight affects happiness (mood) of kindergarten students. Two groups of kindergarten students are tested in two cities – Seattle (57 sunny days per year) and Miami (175 sunny days per year); happiness is measured on a Likert scale of 1 to 5.

**Solution**

a)

b)

c)

d)

**Scenario 9**

A researcher wants to determine the effects of various beverages on the energy level of college indoor track runners during a meet. Three groups of n=15 in each were given either a fruit juice, Gatorade, or water 2 hours prior to the track meet. Upon completion of their run, all of the participants were given a questionnaire that asked them their perceived energy levels during the run on a scale of 1 to 10. Median energy levels among the 3 groups were compared.

**Solution**

a)

b)

c)

d)

**Scenario 10**

Researchers are interested in knowing if there is a significant difference among depression scores of students who receive certain types of therapy. Students are assigned to 1 of 3 therapy groups: journal and counseling therapy, journal therapy only, or counseling therapy only. The researchers control for pre-test depression scores.

**Solution**

a)

b)

c)

d)

Statistics and Probability