Exam 11: More on Experiments: Confounding and Obscuring Variables

Armand conducts a study for his research method class. He is curious as to whether watching romantic movies makes people more committed to their romantic relationship. He collects a sample of men in dating relationships and divides them into two groups. One group watches a 5-minute clip of a movie in which the main characters are having a romantic first date. The second group watches a 5-minute clip from the same movie in which the main characters break up. After the participants watch the movie clip, they are then asked to write a sentence about their relationship. Armand counts the number of uses of the words we and us as a measure of commitment. After conducting the study, he finds that there is not a statistically significant difference between his two groups. Armand's professor suggests that the null effect may be due to insufficient between-group variance. Describe two ways that Armand's study may have had poor between-group variance.

Which of the following studies would NOT have a possible threat of observer bias?

A researcher's attempt to control sounds, smells, and even temperature in a testing environment is meant to reduce which of the following?

Dr. Paddock is a counseling psychologist who is interested in decreasing adjustment issues in first-year college students. She is curious if having students create collages of their first few weeks of school and then mail them home will help students feel they have integrated their new life with their old and, as a result, will help them feel less homesick. She samples a group of 100 incoming college freshmen at her university and measures how homesick they are during the first week of school. During week 4 of school, she has them make the collage and send it home. During week 7 of school, she measures their homesickness again. She notices a significant reduction in the amount of homesickness from the pretest to the posttest and concludes that her treatment is effective. What is a comparison group? What kind of comparison group could Dr. Paddock add to her study to address several threats to internal validity? (In other words, what would this comparison group do/not do?) Explain why this addition would help address threats to internal validity.

In previous studies, Dr. Schulenberg has established that finding meaning in one's everyday work activities can lead to greater success in the workplace (e.g., productivity, creativity). He is curious as to whether this can happen in the college classroom. Specifically, he is curious whether finding meaning in one's classroom experience can lead to greater academic performance. In the spring semester, he has his teaching assistant randomly assign half the class to write a paragraph each class period about how the material has meaning for their lives (meaning group). The other half writes a paragraph about what they did to prepare for class (preparation group). He does not know which of his students are writing which paragraph, and the students are not aware they are responding to different writing assignments. To measure academic performance, he gives the students a midterm essay exam and a final exam. Imagine that in Dr. Schulenberg's study, he notes that all of the students do extremely well on the midterm exam. When he looks at the results of the final exam, he notices that all the students' exam scores went down. Given this information, which of the following threats might be present in his study?

Testing threats involve , whereas instrumentation threats involve .

In what way does high within-groups variance obscure between-groups variance?

Name the three threats to internal validity that can occur in studies regardless of the use of a comparison group. Why doesn't a comparison group help in these cases?

Dr. Paddock is a counseling psychologist who is interested in decreasing adjustment issues in first-year college students. She is curious if having students create collages of their first few weeks of school and then mail them home will help students feel they have integrated their new life with their old and, as a result, will help them feel less homesick. She samples a group of 100 incoming college freshmen at her university and measures how homesick they are during the first week of school. During week 4 of school, she has them make the collage and send it home. During week 7 of school, she measures their homesickness again. She notices a significant reduction in the amount of homesickness from the pretest to the posttest and concludes that her treatment is effective. Imagine in Dr. Paddock's study that the pretest scores were incredibly high, indicating a large amount of homesickness in her sample. What kind of threat to internal validity does this pose? How does this affect her conclusion that her treatment for homesickness worked?

Dr. Hoff is curious as to whether children in a kindergarten classroom will be friendlier after talking about friendship. Immediately before and after the discussion, she has several undergraduate research assistants code the "friendliness" of a group of kindergarteners. Which of the following threats should Dr. Hoff be most concerned about?

In previous studies, Dr. Schulenberg has established that finding meaning in one's everyday work activities can lead to greater success in the workplace (e.g., productivity, creativity). He is curious as to whether this can happen in the college classroom. Specifically, he is curious whether finding meaning in one's classroom experience can lead to greater academic performance. In the spring semester, he has his teaching assistant randomly assign half the class to write a paragraph each class period about how the material has meaning for their lives (meaning group). The other half writes a paragraph about what they did to prepare for class (preparation group). He does not know which of his students are writing which paragraph, and the students are not aware they are responding to different writing assignments. To measure academic performance, he gives the students a midterm essay exam and a final exam. Which of the following aspects of Dr. Schulenberg's study allows him to prevent observer bias?

A confound that keeps a researcher from finding a relationship between two variables is known as a(n) confound.

To be a history threat, the external event must occur:

Which of the following things can be done to reduce the effect of individual differences?

Why is there a publication bias against null effects?

Dr. LaGuardia is curious as to whether children in a daycare center will share more after watching an educational video on sharing. Immediately before and after the video, he has several undergraduate research assistants code the sharing behavior of a group of 33 four-year-olds. Which of the following would you recommend to him to decrease the threat of instrumentation?

In previous studies, Dr. Schulenberg has established that finding meaning in one's everyday work activities can lead to greater success in the workplace (e.g., productivity, creativity). He is curious as to whether this can happen in the college classroom. Specifically, he is curious whether finding meaning in one's classroom experience can lead to greater academic performance. In the spring semester, he has his teaching assistant randomly assign half the class to write a paragraph each class period about how the material has meaning for their lives (meaning group). The other half writes a paragraph about what they did to prepare for class (preparation group). He does not know which of his students are writing which paragraph, and the students are not aware they are responding to different writing assignments. To measure academic performance, he gives the students a midterm essay exam and a final exam. The study described above is an example of which of the following?

When a double-blind study is not possible, an acceptable alternative may be .

Unsystematic variability in a study is also known as:

Dr. Anderson conducted a study investigating whether exercising immediately before an exam boosted cognitive abilities. She randomly assigned participants to either do jumping jacks or count to 60 before giving them a geometry test. She did not find any differences between groups but believes there may have been a ceiling effect. What might be a clue that this was the case?