Chapter 11 for RM

Frances decides to conduct a second study on concreteness and memory in a laboratory setting. She creates a list of 12 concrete items (e.g., pencil and table) and a list of 12 abstract items (e.g., justice and freedom). Participants view each word for 1 second and then recall them in order. The study shows a null effect, and almost all the participants remembered all the words on both lists. Frances' study has a null effect likely because of _____, which led to ______ variability. To eliminate this problem, Frances should consider making the task ______.

1. a ceiling effect 2. not enough between-groups 3. more difficult

Lucia is interested in studying discrimination in hiring. She designs an experiment in which participants take the role of an employer looking at job candidates for a specific position. Each participant is given two very similar résumés (one for a candidate with a stereotypically female name and one for a candidate with a stereotypically male name) and is then asked to rate the suitability of each candidate for a job. Lucia finds no difference in participants' ratings of male and female candidates. Lucia should be most concerned about ________ in her study. She should consider using _______ with two different groups of participants to address this threat.

1. demand characteristics 2. a double-blinded study

Power increases with a________ sample. The results of a study with this type of sample would have a ________ CI and would be more likely to be ______ in future studies.

1. larger 2. narrow 3. replicated

Null effects can be caused by excessive amounts of unsystematic variance, or _______. This within-groups variability can be caused by dependent variable with poor reliability or by faulty data collection, which is referred to as ______. It can also be caused by _______ if variations in participants' characteristics obscure changes brought on by the manipulation. Finally, outside factors in the experimental setting can influence participants, otherwise referred to as ______.

1. noise 2. measurement error 3. individual differences 4. situation noise

If a researcher determines that the independent variable makes no significant difference in the dependent variable, they are concluding a(n) ______. This could either be the truth (the variables really are not related) or be due to design flaws in the experiment. There are several design flaws that may produce such a result. A(n) _______ can occur when the change in the independent variable is not strong enough to affect the dependent variable. Or the dependent variable might not be responsive enough to detect change from the independent variable; in other words, it could be a(n)________. Additionally, scores from the dependent variable can spontaneously cluster near the top of possible scores, known as the _______, or near the bottom of possible scores, known as the _______ these phenomena can make covariance undetectable.

1. null effect 2. weak manipulation 3. insensitive measure 4. ceiling effect 5. floor effect

The influence of a researcher's own expectations on how they view outcomes in an experiment is called _____. This can be prevented by making sure that researchers are unaware of which participants are in which conditions, called a(n) _______. To further reduce this issue, the conditions can sometimes be unknown to both the experimenter and the participant, called a(n) _______.

1. observer bias 2. masked design 3. double-blind study

Frances is conducting a study on concreteness and memory in her dorm room with several of her hallmates. She creates a list of 12 concrete items (e.g., pencil and table) and a list of 12 abstract items (e.g., justice and freedom). Her hallmates view each word for 1 second and then recall them in order. Contrary to Frances' prediction, the study shows a null effect. The study has a null effect likely because of ______, which led to _______ variability

1. situation Nosie 2. too much within-groups

Some threats to internal validity can be addressed simply by including a comparison group, whereas other threats to internal validity can occur even in studies with a comparison group. The inclusion of a comparison group would help to avoid which of the following threats to internal validity?

Avoided Threat(s): history threat maturation threat regression to the mean Not Avoided Threat(s): observer bias demand characteristics

Which of the following strategies are potential ways to prevent individual differences from obscuring group differences?

Correct Answer(s): increase the number of participants use a within-groups design Incorrect Answer(s): use an independent-groups design use validated scales

Which of the following strategies are potential ways to prevent individual differences from obscuring group differences?

Correct Answer(s): increase the number of participants use a within-groups design Incorrect Answer(s): use validated scales use an independent-groups design

Which of the following validities are threatened by observer bias in an experiment?

Correct Answer(s): internal validity construct validity Incorrect Answer(s): external validity statistical validity

Which of the following strategies are potential ways to avoid testing threats?

Correct Answer(s): use alternative forms of the test use a posttest-only design add a comparison group Incorrect Answer(s): remove participant scores from the pretest use a masked design

Which of the following validities are threatened by observer bias in an experiment?

Correct Answer: construct validity internal validity Incorrect Answer: external validity statistical validity

Which of the following are factors that can contribute to a null effect in a study?

Factor(s) weak manipulation floor effect situation noise Not Factor(s): too much power large sample size

All else being equal, which of the following are methods that can help increase power in a study?

Method(s): increasing sample size using a within-groups design Not Method(s): adding situation noise using an independent-groups design

Which of the following are obscuring factors that can be detected with a manipulation check?

Obscuring Factor(s): ceiling effects floor effects weak manipulations Not Obscuring Factor(s): situation noise individual differences

Wanda guesses that older children will be more likely to share than younger children. She observes the older children on the playground more closely and notices they do share at a high rate.

Observer bias

Dr. Tran wants to examine the effectiveness of group therapy sessions on drinking behavior. She recruits college students as her participants and randomizes the participants into two groups: a structured-session group and an unstructured-session group. The structured-session group attends 10 sessions that Dr. Tran facilitates. The unstructured-session group attends 10 sessions that members of the group facilitate. Match each threat to internal validity to the corresponding scenario that might happen in Dr. Tran's study.

Regression threat: On the first day of the sessions, all of the participants state that they participate in binge drinking 7 days a week. At the end of the study, all of the participants report a significant reduction in drinking selection-attrition threat: Several participants in the structured group stop attending after just a couple of sessions, while all members of the unstructured group continue to attend their sessions regularly. selection-history threat: When Dr. Tran measures drinking behavior in the last week of the sessions, all of the students in the unstructured group have an exam coming up, while the students in the structured group do not.

Samira finds these results in her study on binge-watching TV and relationship quality: d = −0.13, 95% CI [−.30, .40]. Her variables had good construct validity and she had an adequate sample size. What should Samira do based on the results of her study?

Samira should conclude that there truly is no significant effect and revise her theory.

Feliciano is using a pretest/posttest design to conduct an experiment on improving children's handwriting, employing two different techniques of improving handwriting and a control condition. In the results, the two groups who receive the treatment don't show any difference from each other. Feliciano believes that there is a difference but that his 3-point assessment scale of handwriting cannot detect it. Identify the true and false statements about Feliciano's study.

True Statement(s): Feliciano is most concerned about using an insensitive measure. To address his concern, Feliciano should use a scale with more levels for his dependent variable. False Statement(s): Feliciano is most concerned about measurement error. To address his concern, Feliciano should increase his sample size. To address his concern, Feliciano should use a manipulation check for his independent variable.

Identify the true and false statements about null effects.

True Statement(s): If there is not enough between-groups difference, it can result in a null effect. Null effects can occur in any experiment. False Statement(s): Researchers rarely find null effects in experiments. Decreases in within-groups variability can lead to a null effect.

Identify the true and false statements about the placebo effect.

True Statement(s): The placebo effect can be addressed by including a control group that does not receive anything. The placebo effect can be addressed by using a double-blind placebo control study. Placebos have an effect because people believe in the effectiveness of the treatment they think they are receiving. False Statement(s): The placebo effect can be addressed by randomly assigning participants to conditions. Patients receiving a placebo do not experience relief in their symptoms.

Jared wants to examine whether mindfulness training can increase concentration. He begins with a concentration task and finds that on average his participants can concentrate for only 30 seconds. He then gives the participants mindfulness training over the course of 2 weeks and finds that their average score improves significantly to 30 minutes on the same concentration task. Identify the true and false statements about Jared's study.

True Statements(s): Jared should include a comparison group to address the threat in his study. Jared's study has a regression threat. False Statement(s): Jared should use a masked design to address the threat in his study. Jared's study has an instrumentation threat.

Identify the true and false statements about threats to internal validity in one-group, pretest/posttest designs.

True Statements: If participants withdraw from a study in an unsystematic way, there is likely no attrition threat. A regression threat can produce a significant result that does not actually exist in the population. False Statements: A study typically has only one threat to internal validity. To prevent a history threat, the comparison group should be studied at a different time or in a different location than the treatment group.

Identify the true and false statements about null effects.

True statement(s): It is possible for researchers to find null effects because the independent variable really does not cause a significant difference. Measurement error causes null effects because it leads to high within-groups variability. Studies with null effects should be replicated and included in meta-analyses. False Statement(s): Null effects only happen in posttest-only designs. Researchers should not report null effects because they are not informative.

All 50 students get all 10 test questions correct, regardless of the review session they are in.

ceiling effect

Antonio is studying how different pamphlets promoting a local charity might increase volunteer behavior in high school students. He creates one pamphlet that shows students having fun and being social while volunteering, and another that discusses the benefits volunteering has for college applications and future careers. Antonio has participants read one pamphlet or the other and then fill out a questionnaire about their intentions for volunteering in the future. Antonio's questionnaire asks participants to rate how likely they are to volunteer in the future on a scale of 1 ("I will not volunteer at all") to 5 ("I will likely volunteer in the future"). Antonio finds that both groups score an average of 4.8 on his measure. What problem is most likely causing a null effect in Antonio's study?

ceiling effect

Darnell has his participants look through fashion magazines and then rate their level of body satisfaction. His participants all rate lower satisfaction with their bodies after looking at the magazines.

demand characteristics

Zion is investigating the effectiveness of his summer math tutoring program. He randomly assigns elementary school students to a tutoring group, which receives the math tutoring program 3 days a week during the entire break, or a self-study group, which receives a sample of math materials without a tutor. At the end of the summer, all of the students take the same math test with a possible score of 0 to 100. The students in the tutoring group are proctored by a strict and intimidating teacher, while the students in the self-study group are proctored by a friendly and approachable teacher. Zion finds these results: d = 0.15, 95% CI [−.30, .45]. What is the most likely explanation for Zion's results?

design confounds acting in reverse

All 50 students get all 10 test questions incorrect, regardless of the review session they are in.

floor effect

A city in California has asked Professor Rodriguez to conduct an experiment on earthquake preparedness. Professor Rodriguez will assess the preparedness of a random sample of residents in the city, and then the city will mail out an annual brochure on earthquake safety. Then, 2 weeks later, he will again assess the preparedness of those residents. Right after the brochures are mailed, a large earthquake is reported in Japan. Which threat to internal validity is present in Professor Rodriguez's experiment?

history threat

Professor Zhao measures the effectiveness of the review sessions with pass/fail categories. He finds that there is no difference between the students in the two review sessions.

insensitive measure

Initially, raters are quite strict in their ratings of prosocial behavior in videotapes of a preschool class, but after 3 hours of rating, their criteria become more lenient.

instrumentation threat

Label each issue with the solution that would best prevent within-groups variability from obscuring group differences.

measurement error: reliable, precise scales more measurements situation noise: experimental control individual differences: within-groups design

A graduate student predicts that people eating sweets will be friendlier than people eating healthy foods. She has one group of participants eat donuts and interact with one another. She has another group of participants eat carrot sticks and interact with one another. She codes each participant's level of friendliness.

observer bias

Jahlil wants to find out whether his new self-esteem intervention is effective. One group gets his new intervention, and another group gets a friendly conversation with Jahlil. At the end, he finds that both groups have a boost in self-esteem.

placebo effect

Jennie creates a new healthy eating seminar. She asks her participants whether they would like to sign up for her new seminar or receive a pamphlet instead. At the end of her study, she finds that the seminar group reports healthier eating habits than the pamphlet group.

selection effect

Jermaine is curious whether the way students take notes affects their academic ability. He recruits two groups of students: one group of high achievers and one group of low achievers. He then asks both groups to take notes in the exact same way to see how it will affect their scores. During the study, several students in the low-achieving group drop out from the study, as they find the notetaking task difficult. At the end of the study, the results for each group are similar. What threat to internal validity may be present in Jermaine's experiment?

selection-attrition threat

Candice has created an intervention to find out whether using imagination increases children's spatial reasoning abilities. She randomly recruits kindergarteners from city schools and pretests them with a spatial reasoning task. After a week of her intervention, she measures the children's spatial reasoning again using the same survey. All the children score better on the assessment the second time compared with the first. What threat to internal validity may be present in Candice's experiment?

testing threat

On Monday, an instructor has his class sit in chairs for 2 minutes before completing a reading quiz. On Wednesday, he has the same class do 2 minutes of jumping jacks before completing the same reading quiz that they took on Monday.

testing threat

Kunene creates an experiment to investigate whether viewing pictures on different types of social media sites causes people to feel more or less social. She has participants look at pictures on a website with either a Facebook logo or an Instagram logo, but everything else about the website is the same. Kunene measures sociability using a questionnaire that asks participants to rate themselves on a scale of 1 to 10 in response to several questions, such as "How interested are you in meeting other people right now?" and "How interested are you in talking to your friends right now?" Kunene finds that both groups have sociability averages around 6. What problem is most likely causing a null effect in Kunene's study?

weak manipulation

The review sessions are different in that one is held in-person and the other is held through video conferencing, although they both cover the same content.

weak manipulation