Professor Wilson wished to investigate whether background music affects comprehension. Twenty undergraduate students (twelve female) volunteered to take part in the experiment, which involved reading a complex passage and then answering twenty questions on its meaning. Comprehension was measured by the number of questions answered correctly.
Half of the participants performed the comprehension task first whilst a rock album by Led Zeppelin was played at a medium volume in the room. After a delay of 15 minutes these participants then performed the comprehension task again (with a different passage and questions) but this time with the room in silence.
The procedure for the other half of the participants was exactly the same, except that there was silence in the room the first time they performed the comprehension task, and the music was played for the second performance of the task.
Q1 What is the independent variable? Specify its different levels.
Q2 What is the dependent variable?
Q3 Name the type of experimental desigin.
Q4 State the null hypothesis (H0) and alternative hypothesis (H1).
Q5 Is H1 a one-tailed or a two-tailed hypothesis?
Q6 What is the possibly confounding variable, and how did the experimenter control for it?
Professor Perkins has collected anxiety scores from 25 participants and wants to calculate a Z score for the sample mean of 26. She's found out that the population of anxiety scores from individuals has a mean () of 25 and a standard deviation () of 5.
Q9 What are the mean and standard error of the appropriate sampling distribution?
Q10 What's the Z score for the sample mean?
