Exam 11: More on Experiments: Confounding and Obscuring Variables

When interrogating experiments, on which of the big validities should a person focus?

RESEARCH STUDY 11.4: 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. Provide three reasons why Armand's study may have resulted in null effects.

Spontaneous remission in clinical studies is an example of which of the following threats to internal validity?

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

Ceiling effects can affect:

Dr.Gong conducts a study where she randomly assigns participants to different experimental conditions.The testing for each condition occurs in a different room of the psychology building.After collecting her data, she learns that the air conditioning in one of the rooms had been turned off during data collection.Which of the following threats to internal validity should Dr.Gong be concerned with?

What can researchers do to reduce the risk of measurement error?

RESEARCH STUDY 11.3: 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 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 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?

RESEARCH STUDY 11.3: 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 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 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.

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

Using the same setting and consistent protocols for each participant in a study will reduce the effect of:

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

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

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

RESEARCH STUDY 11.4: 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. Armand's professor proposes that he replicate the study and double the number of participants he recruits.State which cause(s) of within-group variability will be helped by adding more participants and why this will help.

RESEARCH STUDY 11.3: 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 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.

Observer bias can threaten which of the following big validities?

RESEARCH STUDY 11.3: 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 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?

RESEARCH STUDY 11.4: 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. 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 .