Question 1

Bill conducted an experiment to determine the effectiveness of a drug prevention program in high school.This group was compared to students at another high school that did not take part in the program.The students were given an exam before and after taking part in the program.As the students completed the posttest,many realized that it was the same test they took before the program and put in random answers,as teenagers would.This is a case of what invalidity problem?

Accepted Answer

This is an example of the testing invalidity problem, where taking the pretest affects the results of the posttest. In this case, the students recognized the test and put in random answers, which would not accurately reflect their knowledge or understanding of the material.

Question 2

Joelle was conducting a six-month experiment in which she was interviewing members of the community to determine if a new police-community outreach program increased positive perception of police officers amongst the community.Four months into the experiment,a scandal regarding police brutality hit the news in a neighboring city,which had an effect upon this community's perception of police.Which source of internal invalidity does this example reflect?

Accepted Answer

This example reflects the source of internal invalidity known as history, as an external event (the police brutality scandal in a neighboring city) occurred and may have affected the participant's perception of the police officers being interviewed.

Question 3

When we are concerned that because of media coverage of violence in schools that research participants' ideas and attitudes about the topic of gun control have changed between the time we first measured them and the second time we measured them after the treatment was administered,we are dealing with the threat to internal validity known as

Accepted Answer

History refers to external events or factors that may influence the participants' responses and is the most appropriate choice in this scenario since media coverage of violence in schools is an external factor that may affect the results of the study. Selection bias, maturation, testing effect, and mortality do not apply in this context.

Question 4

Subjects who leave an experiment before it is completed is an example of _______.

Accepted Answer

Mortality refers to the loss of participants during the course of an experiment or study. This loss can lead to biased results and reduced statistical power. Therefore, subjects who leave an experiment before it is completed is an example of mortality.

Question 5

To match experimental and control group preferences,a researcher needs:

Accepted Answer

A quota matrix can be used to ensure that the experimental and control groups are matched on relevant characteristics, such as age, gender, or prior experience, which may affect their preferences. This helps to minimize the potential confounds and increase the internal validity of the study. The other options do not directly address the issue of group matching. A double-blind study is used to prevent bias in the administration and interpretation of the treatment or intervention, but it does not ensure group equivalence. A pretest and a posttest are used to measure the change or difference in the dependent variable between the two groups, but they do not control for the initial differences. Compensation is a form of payment or reward for participation, but it does not affect group matching.

Question 6

In evaluating how effective an anti-bullying program in a school is,Iori asks students how many times they have been bullied in the past four months at the beginning and middle of the semester.However,since he did not use a control group,what form of invalidity may be a problem?

Accepted Answer

Maturation is a form of invalidity that occurs when changes in the participants' behavior are due to natural maturation processes rather than the intervention being tested. Without a control group to compare the results to, it is impossible to determine if any changes in the bullying frequency reported by the students are due to the anti-bullying program or maturation. Compensation refers to the phenomenon in which participants try to please the experimenter or compensate for the intervention, but this is not relevant to this scenario. Statistical regression describes when extreme scores tend to regress towards the mean in subsequent measurements, but again, this is not relevant. Experimental mortality refers to participants dropping out of the study or being lost to follow-up, which is also not a concern in this scenario. Causal time order refers to the requirement that the cause must precede the effect, which is not relevant in this case.

Question 7

As a longitudinal experiment,Juan worked with two different groups,one who was receiving a special stress-reduction training,and another who was not.These two groups were matched together on important variables,and a pretest and posttest were both performed.However,he noticed that after sessions the individuals in the stress-reduction training were telling those in the control group about what they did each day.What form of internal invalidity is this?

Accepted Answer

Diffusion or imitation of treatments occurs when individuals in the control group become aware of the treatment being received by the experimental group and try to replicate it. In this case, it seems that individuals in the stress-reduction training group were talking about their experiences with those in the control group, potentially leading to diffusion of the treatment.

Question 8

Misty did an experiment in which half of her subjects were told that they had extrasensory perception and half were not.In reality,there was no difference.Interestingly,at the end of the three-month experiment,those subjects who were told that they had extrasensory perception actually outscored the control group on the ability to accurately describe video scenes with the sound turned off.This example reflects

Accepted Answer

The scenario described is an example of the Pygmalion effect, which is also known as the self-fulfilling prophecy. This effect occurs when expectations of a person or group can influence their behavior and ultimately lead to the expected outcome. In this case, the subjects who were told they had extrasensory perception had higher expectations placed upon them, which led to them performing better on the video scene description test.

Question 9

From a scientific perspective,the preexperimental design that provides the weakest evidence of a relationship between dependent and independent variables is the

Accepted Answer

The one-shot case study is the preexperimental design that provides the weakest evidence of a relationship between dependent and independent variables as it lacks a control group and a pretest to establish a baseline for comparison.

Question 10

A new program designed to boost math scores based on different teaching strategies is enacted in a classroom.Neither the teacher,nor the students know specifically that they are the experimental group in this research project.This would be an example of

Accepted Answer

In a double-blind experiment, neither the participants nor the researchers know which group is the experimental group and which group is the control group. This helps to eliminate bias and ensures that the results are more reliable. In this scenario, since neither the teacher nor the students know they are the experimental group, it is an example of a double-blind experiment.

Question 11

The problem of external validity refers to the generalizability of results.

Accepted Answer

The problem of external validity is indeed related to the generalizability of results obtained in a study and its applicability to other populations, settings or contexts.

Question 12

A researcher was conducting an experiment on a new method to reduce fear of flying and did not use a control group.During this experiment,a high-profile plane crash was reported in the media.What threat to internal validity is this?

Accepted Answer

The high-profile plane crash reported in the media is considered a historical event that could potentially affect the outcome of the experiment. Since there was no control group, it is impossible to determine whether the fear reduction method had any effect or if the results were caused by the external factor of the plane crash.

Question 13

Howard Schuman argues that experimental research can be specifically useful in helping with what other form of research?

Accepted Answer

Howard Schuman argues that experimental research can be specifically useful in helping with survey design. Experimental research can help design better questions and validate survey measures to improve their reliability and validity.

Question 14

When events (e.g.life stressors)outside of the researcher's control have the likelihood to affect a participant's response,especially in longitudinal studies,this threat to validity is

Accepted Answer

History refers to events outside of the study that occur during the study and may affect participants' responses. This is especially relevant in longitudinal studies, where participants are followed over an extended period of time and may experience various life stressors or events that could impact their responses. Maturation refers to changes that occur naturally over time (e.g. aging) and may impact participants' responses. Mortality refers to participants dropping out of the study, which could bias the results if those who drop out have different characteristics than those who remain. Statistical regression refers to a phenomenon where extreme scores on a measure tend to move closer to the mean on subsequent measurements, regardless of intervention or treatment. Testing refers to the fact that participants' scores may be impacted by taking the same test multiple times, as they may become more familiar with the test and improve their scores independent of any treatment or intervention.

Question 15

The Hawthorne effect most clearly demonstrates the need for

Accepted Answer

The Hawthorne effect refers to the phenomenon where participants modify their behavior simply because they are being studied. This underscores the importance of having a control group or comparison condition in order to isolate the effects of the independent variable (in this case, the manipulation being studied) from extraneous variables such as participants' awareness of being studied. Therefore, choice C - a control group - is the best option.

Question 16

Latona did an experiment at a military barracks over the space of a few months to examine the effect of group size on group morale.He randomly assigned soldiers to the experimental and control groups and did a pretest and posttest.Midway through the experiment,some of the soldiers were re-assigned to different stations across the U.S.causing the sample size to drop.Which source of internal invalidity does this example reflect?

Accepted Answer

This example reflects mortality, as the loss of participants due to re-assignment impacted the sample size and potentially the representativeness of the remaining participants.

Question 17

In an experiment where neither the physicians nor the subjects know who was receiving the experimental drug or placebo is an example of a

Accepted Answer

A double-blind experiment is one in which neither the physicians nor the subjects know who was receiving the experimental drug or placebo. This type of experiment is designed to reduce the potential for bias or placebo effects in the results. All other choices are either incorrect or do not accurately describe this type of experiment.

Question 18

Lyle conducted a study to determine if a new class program could increase the test performance of students with high functioning autism.His experiment specifically included those students who already had high test scores.He should be concerned about which potential form of internal invalidity in his experiment?

Accepted Answer

Statistical regression is a concern because the study involves students who already have high test scores, and their scores might regress to the mean over time, making it seem like the program had an effect when it might not have.

Question 19

"Natural" experiments refers to experiments which

Accepted Answer

Natural experiments occur naturally without the experimenter's intervention. They are not manipulated by the experimenter, but rather are observed and analyzed for cause-and-effect relationships. The other options are incorrect as they do not accurately describe what a natural experiment is.

Question 20

To ensure that all your participants have an equal opportunity to be in either experimental group (one receives a drug,the other group receives a placebo),you decide to toss a coin to determine who gets placed in which group.You have engaged in _______.

Accepted Answer

Random assignment is the process of assigning participants to experimental groups in a way that every individual has an equal chance of being placed in either group. By randomly assigning participants, bias and confounding variables can be minimized, and the results can be more confidently attributed to the intervention being tested.

Quiz 8: Experiments