Exam 10: More on Experiments: Confounding and Obscuring Variables

RESEARCH STUDY 10.3 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 mailing 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. -Refer to Research Study 10.3 above to answer the following question. Name two threats to internal validity that are possibly present in Dr.Paddock's study.What other explanation do these threats provide for the results found by Dr.Paddock?

RESEARCH STUDY 10.4 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. -Refer to Research Study 10.4 above to answer the following question. Armand's professor suggests that the null effect may be due to a large amount of within-group variance.State three causes of within-group variance in Armand's study.

RESEARCH STUDY 10.1 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 different writing assignments. To measure academic performance, he gives the students a midterm essay exam and a final exam. -Refer to Research Study 10.1 above to answer the following question. Dr.Schulenberg likely designed his study so that neither he nor his students knew which group they were in to address which of the following?

RESEARCH STUDY 10.1 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 different writing assignments. To measure academic performance, he gives the students a midterm essay exam and a final exam. -Refer to Research Study 10.1 above to answer the following question. Which of the following aspects of Dr.Schulenberg's study allows him to prevent observer bias?

RESEARCH STUDY 10.3 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 mailing 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. -Refer to Research Study 10.3 above to answer the following question. 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.

Regression is especially problematic in which of the following situations?

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

RESEARCH STUDY 10.3 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 mailing 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. -Refer to Research Study 10.3 above to answer the following question. Imagine in Dr.Paddock's study that only 90 of the original participants completed the measure of homesickness during Week 7 (10 participants had left the university and were unavailable).Name two things that Dr.Paddock can do to address this possible threat to internal validity and why these should be done.

Which of the following cannot be found in a one-group,pretest/posttest design?

Which of the following is true of instrumentation threats?

Dr.Whetstone 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 NOT recommend to her as a way to address this type of threat?

RESEARCH STUDY 10.1 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 different writing assignments. To measure academic performance, he gives the students a midterm essay exam and a final exam. -Refer to Research Study 10.1 above to answer the following question. The study described above is an example of which of the following?

Dr.Sanderson is curious as to whether exposing people to violent video games causes them to be more aggressive.She assigns half her participants to play a violent video game for 5 minutes and the other half to play the same game for 25 minutes.Afterward,she has them play a board game and has a well-trained coder determine whether they are very aggressive in their playing style,barely aggressive,or not at all aggressive.She finds that a vast majority of her participants,regardless of group assignment,are rated as very aggressive.This outcome would be known as a/an:

Which of the following is true of testing effects?

Name two study designs that would address issues of individual differences contributing to within-group variance.If these two designs are not possible,what else could a researcher do?

Explain why null effects are important in science but are hard to find in the popular press.

Dr.LaGuardia is curious as to whether children in a daycare center will share more after watching an education 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 her to decrease the threat of instrumentation?

Dr.Deveraux has conducted a study that has resulted in a null effect.Nonetheless,she suspects that there truly is a causal relationship between her independent and dependent variables.Which of the following might be to blame?

Which of the following is NOT a reason that a study must yield a null result?

RESEARCH STUDY 10.4 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. -Refer to Research Study 10.4 above to answer the following question. 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.