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.

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

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

Dr.Bloedorn is a health psychologist who researches nutrition.She is curious as to whether a new drink additive will help people consume fewer calories during a meal.The drink additive is a white,odorless,tasteless powder that a person can add to any drink.She collects a random sample of 63 overweight students on campus and measures the calories they eat during lunch,using a bomb calorimeter.She then gives this additive to the same 63 participants to use at dinner and measures how many calories they eat (again,using the bomb calorimeter). -Imagine that Dr.Bloedorn finds no difference between the calories consumed with the drink additive and without.This is known as:

Regression is especially problematic in which of the following situations?

Which of the following is NOT a method researchers used to identify or correct for attrition?

Explain what a manipulation check is and how it can be used to address issues of weak manipulations and insensitive measures.

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

Unsystematic variability in a study is also known as:

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 is UNLIKELY to be to blame?

Dr.Bloedorn is a health psychologist who researches nutrition.She is curious as to whether a new drink additive will help people consume fewer calories during a meal.The drink additive is a white,odorless,tasteless powder that a person can add to any drink.She collects a random sample of 63 overweight students on campus and measures the calories they eat during lunch,using a bomb calorimeter.She then gives this additive to the same 63 participants to use at dinner and measures how many calories they eat (again,using the bomb calorimeter). -Which of the following threats to internal validity will Dr.Bloedorn NOT be worried about?

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. -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).What kind of threat to internal validity does this pose? How does this affect her conclusion that her treatment for homesickness worked?

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:

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?

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