Question 1

To assign participants to groups in a truly random fashion, you should:

Accepted Answer

All of these methods (using a random number table, flipping a coin, drawing names out of a hat) are valid ways to randomly assign participants to groups, ensuring each participant has an equal chance of being assigned to any group.

Question 2

External validity in an experiment is most related to:

Accepted Answer

External validity refers to the extent to which the findings of a study can be generalized to other populations or settings. To ensure external validity, it is important to have a representative sample that reflects the characteristics of the larger population. Participant assignment to groups (A), confounding variables (C), and a pretest (D) are all important considerations for internal validity, which refers to the extent to which a study accurately tests the hypothesis it sets out to test.

Question 3

In an experiment, the researcher was unintentionally talkative to one of the participant groups. What best describes the threat to internal validity and why is it a threat?

Accepted Answer

The unintended interaction by the researcher is a threat to internal validity because it introduces a confounding variable (history) that was not part of the independent variable being studied. This can make it difficult to determine whether any observed effects are due to the independent variable or the unintended interaction.

Question 4

Internal validity in an experiment is affected by:

Accepted Answer

Participant assignment to groups affects internal validity because it can create bias in the results. For example, if participants are assigned to groups based on their gender, the results of the experiment may be biased in favor of one gender.

Question 5

Random assignment is to ____ as random selection is to ____.

Accepted Answer

Random assignment refers to assigning participants to different experimental conditions randomly, while random selection refers to selecting participants randomly from the population. Therefore, the best choice is B, where both terms are contrasted correctly as they relate to different aspects of sampling in experimental research.

Question 6

Control in an experiment can be achieved through:

Accepted Answer

Control in an experiment refers to the ability to eliminate or minimize the influence of extraneous variables or factors that could affect the outcome of the study. Random assignment of participants to groups, experimental design, and logic all contribute to achieving control in an experiment. Random assignment helps ensure that any differences between experimental and control groups are due to the intervention being tested and not some other variable. Experimental design is important in controlling for extraneous variables by including factors such as blinding, placebo control, and counterbalancing. Logic also plays a role in controlling for confounding variables by carefully designing the research question and study design. Therefore, option D, which states all of the given choices, is the most appropriate answer.

Question 7

The following experiment illustrates what design?

Accepted Answer

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Question 8

Random assignment of participants to conditions has the advantage over other methods of assignment in that:

Accepted Answer

Random assignment helps in controlling for both known and unknown confounding variables by distributing them equally across all groups, thus minimizing their impact on the outcome of the experiment. This ensures that any differences observed between groups can more confidently be attributed to the manipulation of the independent variable rather than to some other external factor.

Question 9

In a Solomon four-group design:

Accepted Answer

In a Solomon four-group design, only some participants receive a pretest, allowing researchers to assess the effect of the pretest on the outcome.

Question 10

If you are at the point where you are deciding who from the population shall be your participants, you should be using:

Accepted Answer

If you are at the point of deciding who shall be your participants, it is important to use random sampling to ensure that your sample is representative of the population and avoids any potential biases or confounding factors. Random assignment (B) is used once you have selected your participants to assign them to different conditions in your experiment. Factorial design (A) and Solomon's four-group design (C) are experimental designs that are used after the participants have been selected and assigned to conditions.

Question 11

As an experimenter you've identified some confounding variables that you want to control. But you also think there might be some unknown potentially confounding variables. What method of assignment would be most appropriate?

Accepted Answer

Randomization is the best choice because it allows for the even distribution of both known and unknown potential confounding variables across experimental conditions, which minimizes the risk of their influence on the study's outcome.

Question 12

For a study to be considered a true experiment according to Campbell and Stanley, there must be at least ____ level(s) of the independent variable.

Accepted Answer

According to Campbell and Stanley, a true experiment requires at least two levels of the independent variable (such as a treatment group and a control group) in order to establish a cause-and-effect relationship. Randomization is also important for minimizing confounding variables, but it is not the defining characteristic of a true experiment. Therefore, the correct answer is C.

Question 13

If we wish the results of our experiment to generalize, we need to pay special attention to:

Accepted Answer

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Question 14

The following experiment illustrates what design?

Accepted Answer

This experiment has a control group (not exposed to the independent variable) and a posttest (measuring the effect of the independent variable), making it a posttest-only control group design. There is no mention of a pretest, and there is only one independent variable being manipulated, indicating it is not a factorial design or a pretest-posttest design.

Question 15

Random assignment of individuals to groups:

Accepted Answer

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Question 16

A pretest-posttest control group design does not control for:

Accepted Answer

A pretest-posttest control group design can help control for many threats to internal validity such as history, maturation, and regression to the mean. However, it cannot control for the effects of the pretest because the pretest itself may influence the participants' responses or behaviors in the posttest. This is known as the pretest sensitization effect. Mortality is a threat to internal validity that can be controlled by using random assignment and ensuring equal numbers of participants in each group.

Question 17

To select participants from a pool of potential participant, you should not:

Accepted Answer

Selecting names from a list without paying attention to who the individuals are does not ensure a random or unbiased selection, which is crucial for the integrity of research or any selection process aiming for fairness or representativeness.

Question 18

A classmate designs the following experiment. What advice would you give him to improve upon it?

Accepted Answer

Random assignment to groups increases the chance that the groups will be equivalent at the beginning of the study, which strengthens the internal validity of the research design.

Question 19

When assigning participants to groups, you should attempt to control for:

Accepted Answer

It is not feasible or necessary to control for all individual differences, and controlling for only two may not be sufficient. However, controlling for individual differences that are likely to impact the variables being studied based on past research and common sense is a reasonable approach. Sex differences may or may not be relevant depending on the variables being studied, so it is not necessary to always control for them.

Question 20

Which of the following is not a necessary characteristic of a true experiment?

Accepted Answer

A pretest is not always necessary for a true experiment, depending on the research question and design. However, random assignment of participants to groups, control of threats to internal validity, and at least two levels of the independent variable are all necessary characteristics of a true experiment.

Quiz 8: Information-Processing Theory

To assign participants to groups in a truly random fashion, you should:

External validity in an experiment is most related to:

In an experiment, the researcher was unintentionally talkative to one of the participant groups. What best describes the threat to internal validity and why is it a threat?

Internal validity in an experiment is affected by:

Random assignment is to as random selection is to .

Control in an experiment can be achieved through:

The following experiment illustrates what design?

Random assignment of participants to conditions has the advantage over other methods of assignment in that:

In a Solomon four-group design:

If you are at the point where you are deciding who from the population shall be your participants, you should be using:

As an experimenter you've identified some confounding variables that you want to control. But you also think there might be some unknown potentially confounding variables. What method of assignment would be most appropriate?

For a study to be considered a true experiment according to Campbell and Stanley, there must be at least ____ level(s) of the independent variable.

If we wish the results of our experiment to generalize, we need to pay special attention to:

The following experiment illustrates what design?

Random assignment of individuals to groups:

A pretest-posttest control group design does not control for:

To select participants from a pool of potential participant, you should not:

A classmate designs the following experiment. What advice would you give him to improve upon it?

When assigning participants to groups, you should attempt to control for:

Which of the following is not a necessary characteristic of a true experiment?