Ch. 11 – PSY 350

floor effects
Which of the following is NOT one of the three most common threats to internal validity?
She could add a comparison group.
Emma is planning an experiment to examine whether reading to children increases their vocabulary size. She plans to measure the vocabulary size of a group of 18-month-olds, read to them three times a week for three months, then measure their vocabulary size again. How could Emma change the design of the study to remove a major threat to internal validity?
history
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 the city will mail out their annual brochure on earthquake safety. Then, two weeks later, he will again assess the preparedness of those residents. Right after the brochures are mailed, a large earthquake is reported in Japan. What threat to internal validity does this pose?
attrition
Which threat to internal validity occurs when there is a greater systematic loss of participants in one condition than the other condition?
instrumentation
As part of an experiment on the effects of behavior modeling, a set of raters are evaluating the prosocial behavior in a series of videotapes of a class of preschoolers. Initially, the raters were quite strict in their ratings, but after three hours of rating, their criteria had changed. What type of threat to internal validity has occurred?
maturation threats
Some internal validity threats can be addressed simply by including a comparison group, while other internal validity threats can occur even in studies with a comparison group. Which of the following threats to internal validity would be improved with the inclusion of a comparison group?
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selection-attrition threat
Dr. Harrison wants to test the effectiveness of the support group he runs for undergraduates who have drinking problems. He recruits a group of students who have been referred to the counseling center. He randomizes them to two groups — a treatment group and a control group. The treatment group attends 10 structured support group sessions at 8:00 a.m. on Fridays that are facilitated by Dr. Harrison. The control group attends 10 unstructured meetings at 3:00 p.m. on Wednesdays that are facilitated by members of the group. Several of the participants in the treatment group stop attending the group after just a couple of sessions. All of the control group members attend their group regularly. At the end of the 10 weeks of groups, Dr. Harrison measures drinking behavior of the people who are still attending the groups. He finds that the drinking behavior of people who attended all 10 of the structured group sessions is less than the drinking behavior of people who attended all 10 of the unstructured group sessions. What kind of threat to internal validity should Dr. Harrison be concerned about?
large sample size
Which of the following is NOT a problem that may contribute to a null effect in a study?
ceiling effect
The students in a 50-student Introductory Psychology class were randomly assigned to one of two review sessions, each being taught with a different technique. The next day, every student got all 10 of the test questions correct. What problem does Professor Zhao have in determining the better teaching technique for review sessions?
ceiling effect
Which of the following does NOT contribute to within-groups variability?
Use a double-blind study.
Individual differences can contribute to too much within-group variability. Which of the following is NOT a possible solution to individual differences?
insensitive measures
In an experiment on improving children’s handwriting, two different techniques of improving handwriting and a control condition are used. Using a pretest/posttest design, both groups who received the treatment showed more improvement than the control group. However, the two groups didn’t show any difference from each other. The researcher believes that there is a difference, but that the 5-point assessment scale of handwriting cannot detect it. What measurement problem is the researcher concerned with?
regression
Jared is conducting an experiment with ESP (extrasensory perception) training. He begins with a pretest of his 40 participants and divides them into two groups based on their scores. The participants with the 10 lowest scores are given extensive training on how to detect the signals. The participants with the 30 highest scores are given no training. Both groups are retested and the average score of the participants with the training improved, while the average score of the participants without the training actually fell. What threat to internal validity should Jared consider?
demand characteristics
Lucia is interested in studying discrimination in hiring. She designs an experiment in which the participant takes the role of an employer looking at job candidates for a specific position. Each participant is given two very similar resumés—one of a candidate with a female name and one of a candidate with a 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. What threat to internal validity should she be concerned about?
internal validity and construct validity
What two types of validity in an experiment can observer bias threaten?
attrition
Frances did a study to investigate the effect of concreteness on memory. She created a list of 12 items that are very concrete (such as pencil and table) and a list of 12 items that are very abstract (such as justice and freedom). Each item was viewed for one second, then participants recalled them in order. Ten participants were tested in each condition. The study showed null effects. Which is NOT a possible explanation?
maturation
Emma is planning an experiment to examine whether reading to children increases their vocabulary size. She plans to measure the vocabulary size of a group of 18-month-olds, read to them three times a week for three months, then measure their vocabulary size again. What threat to internal validity should she be most concerned about?
She could make it a masked design.
Dr. Robinson designs an intervention that is meant to reduce college students’ risky sexual decisions. She hypothesizes that shaming college students about their risky sexual decisions will improve their decision making. She recruits participants and randomizes them to two conditions—the intervention group and the control group. The sexual behavior of all participants is measured in an interview with Dr. Robinson. After the pretesting, participants who are randomized to the intervention group are scheduled for an individual shaming session with Dr. Robinson. The control group does not participate in the shaming session. One week after the intervention, both groups are interviewed with Dr. Robinson about their sexual behavior over the past week. She finds that the intervention group reported less risky sexual decisions during the posttest interview. How could Dr. Robinson improve the internal validity of her study?
change the design to be within-groups
Frances did a study to investigate the effect of concreteness on memory. She created a list of 12 items that are very concrete (such as pencil and table) and a list of 12 items that are very abstract (such as justice and freedom). Each item was viewed for one second, then participants recalled them in order. Ten participants were tested in each condition. The study showed null effects, and almost all of the participants remembered all of the words on both lists. What is a likely solution?
add more participants
Frances did a study to investigate the effect of concreteness on memory. She created a list of 12 items that are very concrete (such as pencil and table) and a list of 12 items that are very abstract (such as justice and freedom). Each item was viewed for one second, then participants recalled them in order. Ten participants were tested in each condition. The study showed null effects, and large variability within the groups. What is a likely solution?
one-group, pretest/posttest
On the first exam in an Introductory Psychology class, the grades are lower than Professor Mutola expected. She suspects that multitasking is to blame. She bans computers and cell phones from her class between the first and the second exam. When she compares the scores on the two exams, she finds a significant improvement on the second exam. What is the formal name for this type of design?
maturation
On the first exam in an Introductory Psychology class, the grades are lower than Professor Mutola expected. She suspects that multitasking is to blame. She bans computers and cell phones from her class between the first and the second exam. When she compares the scores on the two exams, she finds a significant improvement on the second exam. Professor Mitchell points out that in her classes, students always do better on the second exam because they are more used to her tests. What threat to validity is she suggesting?
attrition
On the first exam in an Introductory Psychology class, the grades are lower than Professor Mutola expected. She suspects that multitasking is to blame. She bans computers and cell phones from her class between the first and the second exam. When she compares the scores on the two exams, she finds a significant improvement on the second exam. When Professor Mutola rechecks her data, she finds that the five students with the lowest scores on the first exam have dropped the class. What threat to internal validity is this?
instrumentation
On the first exam in an Introductory Psychology class, the grades are lower than Professor Mutola expected. She suspects that multitasking is to blame. She bans computers and cell phones from her class between the first and the second exam. When she compares the scores on the two exams, she finds a significant improvement on the second exam. Professor Mutola looks back over the second exam and begins to wonder if it was just an easier exam. What threat to internal validity is she considering?
testing threat
An instructor hypothesizes that doing jumping jacks will improve his students’ quiz performance. On Monday, he has his class sit in their chairs for five minutes before completing a multiple-choice quiz on their reading assignment. On Wednesday, he has his class do two minutes of jumping jacks before completing the same quiz that they took on Monday. The students performed better on the quiz on Wednesday. What is a possible threat to internal validity in this study?
Attrition Threat
In a repeated-measures design or quasi-experiment, a threat to internal validity that occurs when a systematic type of participant drops out of a study before it ends.
Ceiling Effect
An experimental design problem in which independent variable groups score almost the same on a dependent variable, such that all scores fall at the high end of their possible distribution.
Demand Characteristic
A threat to internal validity that occurs when some cue leads participants to guess a study’s hypotheses or goals. Also called experimental demand.
Double-Blind Placebo Control Study
A study that uses a treatment group and a placebo group and in which neither the research staff nor the participants know who is in which group.
Double-Blind Study
A study in which neither the participants nor the researchers who evaluate them know who is in the treatment group and who is in the comparison group.
Floor Effect
An experimental design problem in which independent variable groups score almost the same on a dependent variable, such that all scores fall at the low end of their possible distribution. See also ceiling effect.
History Threat
A threat to internal validity that occurs when it is unclear whether a change in the treatment group is caused by the treatment or by a historical factor or event that affects everyone or almost everyone in the group
Instrumentation Threat
A threat to internal validity that occurs when a measuring instrument changes over time from having been used before. Also called instrument decay.
Manipulation Check
In an experiment, an extra dependent variable researchers can include to determine how well an experimental manipulation worked.
Masked Design
A study design in which the observers are unaware of the experimental conditions to which participants have been assigned. Also called blind design.
Maturation Threat
A threat to internal validity that occurs when an observed change in an experimental group could have emerged more or less spontaneously over time.
Measurement Error
The degree to which the recorded measure for a participant on some variable differs from the true value of the variable for that participant. Measurement errors may be random, if over a sample they both inflate or deflate true scores, or they may be systematic, in which case they may result in biased measurement.
Noise
The unsystematic variability among the members of a group in an experiment. Also called error variance, unsystematic variance.
Null Effect
A finding that an independent variable did not make a difference in the dependent variable; there is no significant covariance between the two. Also called null result.
Observer Bias
A bias that occurs when observers’ expectations influence their interpretation of the participants’ behaviors or the outcome of the study.
One-Group, Pretest/posttest Design
An experiment in which a researcher recruits one group of participants; measures them on a pretest; exposes them to a treatment, intervention, or change; and then measures them on a posttest.
Placebo Effect
A response or effect that occurs when people receiving an experimental treatment experience a change only because they believe they are receiving a valid treatment.
Power
The likelihood that a study will show a statistically significant result when some effect is truly present in the population; the probability of not making a Type II error when the null hypothesis is false.
Regression Threat
A threat to internal validity related to regression to the mean, a phenomenon in which any extreme finding is likely to be closer to its own typical, or mean, level the next time it is measured (with or without the experimental treatment or intervention).
Selection-Attrition Threat
A threat to internal validity in which members are likely to drop out of either the treatment group or the comparison group, not both.
Selection-History Threat
A threat to internal validity in which a historical or seasonal event systematically affects only the subjects in the treatment group or only those in the comparison group, not both.
Situation Noise
Unrelated events, sounds, or distractions in the external environment that create unsystematic variability within groups in an experiment.
Testing Threat
In a repeated-measures experiment or quasi-experiment, a kind of order effect in which scores change over time just because participants have taken the test more than once; includes practice effects and fatigue effects.
Lucia is interested in studying discrimination in hiring. She designs an experiment in which the participant takes the role of an employer looking at job candidates for a specific position. Each participant is given two very similar resumés—one of a candidate with a female name and one of a candidate with a 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. What threat to internal validity should she be concerned about?
Demand Characteristics

-She should be concerned that the participants guessed the manipulation in the study and gave what they thought was the more socially acceptable answer

Which of the following is NOT one of the three most common threats to internal validity?
Floor Effects

-Floor effects are a special case of weak manipulations and insensitive measures, not one of the three most common threats

Frances did a study to investigate the effect of concreteness on memory. She created a list of 12 items that are very concrete (such as pencil and table) and a list of 12 items that are very abstract (such as justice and freedom). Each item was viewed for one second, then participants recalled them in order. Ten participants were tested in each condition. The study showed null effects, and almost all of the participants remembered all of the words on both lists. What is a likely solution?
Change the design to eliminate ceiling effects

-If all of the participants are getting all of the items correct then Frances should make the task more difficult to eliminate the ceiling effect

Which threat to internal validity occurs when there is a greater systematic loss of participants in one condition than the other condition?
Attrition

-Attrition is not a threat if it occurs uniformly across both groups, but if it is systematic it becomes a threat

Frances did a study to investigate the effect of concreteness on memory. She created a list of 12 items that are very concrete (such as pencil and table) and a list of 12 items that are very abstract (such as justice and freedom). Each item was viewed for one second, then participants recalled them in order. Ten participants were tested in each condition. The study showed null effects. Which is NOT a possible explanation?
Attrition

-In a study that only lasts a few minutes, attrition isn’t usually an issue. There was no mention of participant loss.

As part of an experiment on the effects of behavior modeling, a set of raters are evaluating the prosocial behavior in a series of videotapes of a class of preschoolers. Initially, the raters were quite strict in their ratings, but after three hours of rating, their criteria had changed. What type of threat to internal validity has occurred?
Instrumentation

-The raters, who are the measuring instrument, are changing over time

On the first exam in an Introductory Psychology class, the grades are lower than Professor Mutola expected. She suspects that multitasking is to blame. She bans computers and cell phones from her class between the first and the second exam. When she compares the scores on the two exams, she finds a significant improvement on the second exam. What is the formal name for this type of design?
One-Group, Pretest/Posttest

-She is using the first exam as the pretest and the second as the posttest

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 the city will mail out their annual brochure on earthquake safety. Then, two weeks later, he will again assess the preparedness of those residents. Right after the brochures are mailed, a large earthquake is reported in Japan. What threat to internal validity does this pose?
History

-The earthquake is an external or “historical” event that occurs to everyone in the study, therefore the effect of the brochure cannot be assessed

The students in a 50-student Introductory Psychology class were randomly assigned to one of two review sessions, each being taught with a different technique. The next day, every student got all 10 of the test questions correct. What problem does Professor Zhao have in determining the better teaching technique for review sessions?
Ceiling Effect

-Because all the scores are squeezed together at the high end, the effect of the independent variable couldn’t be measured

Jared is conducting an experiment with ESP (extrasensory perception) training. He begins with a pretest of his 40 participants and divides them into two groups based on their scores. The participants with the 10 lowest scores are given extensive training on how to detect the signals. The participants with the 30 highest scores are given no training. Both groups are retested and the average score of the participants with the training improved, while the average score of the participants without the training actually fell. What threat to internal validity should Jared consider?
Regression

-The group that was given training had an unusually bad performance on the pretest, so was likely to regress upward in performance on the posttest, even without training.

On the first exam in an Introductory Psychology class, the grades are lower than Professor Mutola expected. She suspects that multitasking is to blame. She bans computers and cell phones from her class between the first and the second exam. When she compares the scores on the two exams, she finds a significant improvement on the second exam. Professor Mutola looks back over the second exam and begins to wonder if it was just an easier exam. What threat to internal validity is she considering?
Instrumentation

-Instrumentation threat occurs when the pretest and posttest are not sufficiently equivalent

Frances did a study to investigate the effect of concreteness on memory. She created a list of 12 items that are very concrete (such as pencil and table) and a list of 12 items that are very abstract (such as justice and freedom). Each item was viewed for one second, then participants recalled them in order. Ten participants were tested in each condition. The study showed null effects, and large variability within the groups. What is a likely solution?
Adding more participants

-Adding more participants to a study reduces the impact of individual differences within groups and will increase the chance of finding differences between groups

Individual differences can contribute to too much within-group variability. Which of the following is NOT a possible solution to individual differences?
Use a double-blind study

-Double-blind studies can control for observer effects and demand characteristics, but this wouldn’t help with the contribution of individual differences to within-group variability

Dr. Robinson designs an intervention that is meant to reduce college students’ risky sexual decisions. She hypothesizes that shaming college students about their risky sexual decisions will improve their decision making. She recruits participants and randomizes them to two conditions—the intervention group and the control group. The sexual behavior of all participants is measured in an interview with Dr. Robinson. After the pretesting, participants who are randomized to the intervention group are scheduled for an individual shaming session with Dr. Robinson. The control group does not participate in the shaming session. One week after the intervention, both groups are interviewed with Dr. Robinson about their sexual behavior over the past week. She finds that the intervention group reported less risky sexual decisions during the posttest interview. How could Dr. Robinson improve the internal validity of her study?
She could make it a masked design

-While in this case it is not possible for the participants to be blind to their condition, it is possible to make the person assessing the dependent variable blind to group membership, which should make the students more likely to be honest

On the first exam in an Introductory Psychology class, the grades are lower than Professor Mutola expected. She suspects that multitasking is to blame. She bans computers and cell phones from her class between the first and the second exam. When she compares the scores on the two exams, she finds a significant improvement on the second exam. When Professor Mutola rechecks her data, she finds that the five students with the lowest scores on the first exam have dropped the class. What threat to internal validity is this?
Attrition

-The rise in scores on the second test may be due to the loss of these extreme scores, which is attrition

Emma is planning an experiment to examine whether reading to children increases their vocabulary size. She plans to measure the vocabulary size of a group of 18-month-olds, read to them three times a week for three months, then measure their vocabulary size again. How could Emma change the design of the study to remove a major threat to internal validity?
She could add a comparison group

-Adding a comparison group would allow her to show that her intervention had an effect above and beyond the normal effects of maturation

in a study of the span of apprehension or how many objects you can assess after a brief exposure the length of exposure is held constant and the number of objects is varied from one to twelve. After a large number of trails the percentage correct for each number of objects is found. Whats is the dependent variable in this experiment?
the percentage correct (dependent variable is never manipulated)
in a study of the span of apprehension or how many objects you can assess after a brief exposure the length of exposure is held constant and the number of objects is varied from one to twelve. After a large number of trails the percentage correct for each number of objects is found.what is the independent variable?
number of objects
in a word list learning experiment participants are give a list of words to study for 3 minutes and the following a delay are asked to recall the list. The length of time between the study period and the recall is being manipulated: in 2 minutes, 5 minutes or 10 minutes, which of the following is a confounding variable?
All participants in the 2 minutes condition are tested at 8 am those in the 5 minute condition are tested at noon and those in the 10 minute condition are tested at 4 pm
in a word list learning experiment participants are give a list of words to study for 3 minutes and the following a delay are asked to recall the list. The length of time between the study period and the recall is being manipulated: in 2 minutes, 5 minutes or 10 minutes. since different groups need different amounts of time the first 25 participants who arrive are assigned to the 10 minute group the next 25 are assigned to the 5 min group and the final 25 are assigned to the 2 minute group. What confound does this create?
selection effect
Emma is planning an experiment on the effects of being read to on vocabulary size in toddlers. She plans to measure the vocabulary size of a group of 18 month olds, read to them three times a week for month, then measure the vocabulary size again. What threat to internal validity should she be concerned about?
Maturation
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 the city will mail out their annual brochure on earthquake safety. the two weeks later he will again assess the preparedness of those residents. right after brochures are mailed a large earthquake is reported in japan, what threat to internal validity does it poses?
History
a recent study conducted in the Netherlands on the effects of commercials for alcohol or alcohol consumption in the movie theater, found that young adults who consume large amounts of alcohol each week are influenced by the commercials, whereas young adults who consume small amounts of alcohol each week were not influenced. Participants saw one of two types of beverage commercials: alcoholic or nonalcoholic. their consumption of alcohol during the movie was then measured. finally they completed a questionnaire on the drinking habits. What type of design is this?
independent groups factoria
a recent study conducted in the Netherlands on the effects of commercials for alcohol or alcohol consumption in the movie theater, found that young adults who consume large amounts of alcohol each week are influenced by the commercials, whereas young adults who consume small amounts of alcohol each week were not influenced. Participants saw one of two types of beverage commercials: alcoholic or nonalcoholic. their consumption of alcohol during the movie was then measured. finally they completed a questionnaire on the drinking habits.What is a factor in this study?
the movie shown
After reading a report by Rockoff, Yingying is studying the effect of other present and their roles on the rate of gambling bets using a simulated slot machine. Her levels of other present are one, two, or six. Her levels of roles are gamblers and observers. She constructs a 2×3 table of her results of average time between bets. there are two rows for the roles and three columns for the others present. the values in the first row are 15, 15 and 15 and in the second row are 20, 15 and 10. Describe her results.
no effect f role, no effect of others present and an interacrion
maturation threat
a threat to internal validity that occurs when an observed change in an experimental group could have emerged more or less spontaneously over time
history threat
a threat to internal validity that occurs when it is unclear whether a change in the treatment group is caused by the treatment or by a historical factor or event that affects everyone or almost everyone in the group
regression threat
a threat to internal validity related to regression to the mean, a phenomenon in which any extreme finding is likely to be closer to its own typical, or mean, level the next time it is measured
attrition threat
in a repeated measures design or quasi experiment, a threat to internal validity that occurs when a systematic type of participant drops out of a study before it ends
instrumental threat
a threat to internal validity that occurs when a measuring instrument changes over time from having been used before
selection-history threat
a threat to internal validity in which members are likely to drop out of either the treatment group or the comparison, not both
selection-attrition threat
a threat to internal validity in which members are likely to drop out of either the treatment group or the comparison g group, not both
observer bias
a bias that occurs when observers expectations influence their interpretation of the participants behaviors or the outcome of the study
demand characteristics
a threat to internal validity that occurs when some cue leads participants to guess a study’s hypotheses or goals
double blind study
a study in which neither the participants nor the researchers who evaluate them know who is in the treatment group and who is in the comparison group
masked design
a study design in which the observers are unaware of the experimental conditions to which participants have been assigned
double blind placebo controlled study
a study that uses a treatment group and a placebo group and in which neither the research staff nor the participants know who is in which group
null effect
a finding that an independent variable did not make a difference in the dependent variable; there is no significant covariance between the two
ceiling effect
an experimental design problem in which independent variable groups score almost the same on a dependent variable, such that all scores fall at the high end of their possible distribution
floor effect
an experimental design problem in which independent variable group score almost the same on a dependent variable, such that all scores fall at the low end of their possible distribution.
manipulation check
in an experiment, an extra dependent variable researches can include to determine how well an experimental manipulation worked
noise
the unsystematic variability among the members of a group in an experiment
measurement error
the degree to which the recorded measure for a participant on some variable differs from the true value of the variable for that participant. measurement errors may be random, if over a sample they both inflate or deflate true scores, or they may be systematic in which case they may result in biased measurement
situation noise
unrelated events or distractions in the external environment that create unsystematic variability within groups in an experiment
power
the likelihood that a study will show a statistically significant result when some effect is truly present in the population; the probability of not making a type 2 error
Which of the following is NOT one of the three most common threats to internal validity
floor effects
Emma is planning an experiment to examine whether reading to children increases their vocabulary size. She plans to measure the vocabulary size of a group of 18-month-olds, read to them three times a week for three months, then measure their vocabulary size again. How could Emma change the design of the study to remove a major threat to internal validity
She could add a comparison group
Which of the following is NOT a problem that may contribute to a null effect in a study
large sample size
What two types of validity in an experiment can observer bias threaten
internal validity and construct validity
An instructor hypothesizes that doing jumping jacks will improve his students’ quiz performance. On Monday, he has his class sit in their chairs for five minutes before completing a multiple-choice quiz on their reading assignment. On Wednesday, he has his class do two minutes of jumping jacks before completing the same quiz that they took on Monday. The students performed better on the quiz on Wednesday. What is a possible threat to internal validity in this study
testing threat