Refer to the research study below to answer questions 26-29. Dr. Math wondered if children learn multiplication better if they are taught by a teacher wearing a shirt depicting a nice cartoon character rather than a shirt depicting a scary cartoon character. He randomly assigned students to one of two classes. In class A, Mr. Jackson wore a SpongeBob (nice character) shirt while teaching multiplication. In class B, Mrs. Samalez wore a Joker (scary character) shirt while teaching multiplication. All students then took a multiplication test. A suspicion probe indicated that students were unaware of the purpose of the study.   What kind of design is this?

Which of the following is a threat to internal validity found in a within-groups design but NOT an independent-groups design?

Refer to the research study below to answer questions 7-12. Dr. Rem studies sleep and sleep disorders. She is curious as to whether falling asleep in front of a television set causes people to fall asleep more slowly than falling asleep without watching TV. She recruits a sample of 60 women and creates three conditions. All participants come to the sleep lab for three nights in a row and experience all three conditions. In the first condition (A), participants fall asleep in front of a television that is off. In the second condition (B), participants fall asleep in front of a television that is turned on to a 24-hour news channel. In the third condition (C), participants fall asleep in front of a television that is turned on to the same 24-hour news channel but is muted. Participants sleep in the same bed each night. With the use of an electroencephalograph (EEG; a physiological measure that measures electrical activity in the brain), the researcher measures how long it takes participants to fall asleep each night.   What kind of research design is this?

Which type of research design can be used to make causal inferences with the highest level of certainty?

Dr. Ellis is curious about how self-esteem changes as a result of a new counseling program. She is concerned about testing threats in her study. Which of the following would you recommend to her as the best way to address this type of threat?

In testing the effect of noise on task performance, Ernie tests half of the participants in a cool, loud room, and the other half in a hot, quiet room. Ernie’s failure to control the room temperature may result in a(n) _________.

Ray is comparing the heart rates of a group of former smokers to non-smokers after they have walked on a treadmill for 15 minutes. This is an example of a _________.

Within-groups designs may be preferred over independent-groups design because they __________.

If an experiment has a confound, then you cannot tell whether the results are due to the __________.

Refer to the research study below to answer questions 26-29. Dr. Math wondered if children learn multiplication better if they are taught by a teacher wearing a shirt depicting a nice cartoon character rather than a shirt depicting a scary cartoon character. He randomly assigned students to one of two classes. In class A, Mr. Jackson wore a SpongeBob (nice character) shirt while teaching multiplication. In class B, Mrs. Samalez wore a Joker (scary character) shirt while teaching multiplication. All students then took a multiplication test. A suspicion probe indicated that students were unaware of the purpose of the study.   To make sure that the students thought SpongeBob was nice and the Joker was scary, Dr. Math could have _________.