Question 1

_____ occurs when the effects of the independent variable and an uncontrolled variable are intertwined, so one cannot determine which of the variables is responsible for the observed effect.

Accepted Answer

Confounding occurs when the effects of the independent variable and an uncontrolled variable are intertwined, so it becomes difficult to determine which of the variables is responsible for the observed effect. Attrition refers to the loss of participants during a study, fatigue effect refers to a decline in participants' performance due to tiredness or boredom, and counterbalancing is a method used to control order effects in a study.

Question 2

If a greater percentage of heart surgeons than skin doctors are sued for malpractice, can it be concluded that heart surgeons are less competent than skin doctors?

Accepted Answer

Being sued for malpractice is influenced by many factors other than the competence of the doctor, such as the complexity of the procedures being performed or the severity of the patients' conditions. Therefore, it cannot be concluded that heart surgeons are less competent than skin doctors based solely on the fact that a greater percentage of heart surgeons are sued for malpractice.

Question 3

Failure to control some extraneous variables is likely to result in a(n) _____ variable.

Accepted Answer

Failure to control extraneous variables can lead to confounding variables, which can affect the outcome of the experiment and make it difficult to determine the true cause and effect relationship between the independent and dependent variables. Random variables are those that occur randomly and are not under the control of the researcher. Systematic variables are those that are deliberately manipulated by the researcher. Operational variables refer to how a variable is defined and measured in an experiment.

Question 4

Toby wants to see whether packaging information affects the way people rate breakfast cereal. The same cereal is put in three kinds of packages: a brown box that says "To start your day off with a smile"; a yellow box that says "For extra energy all day"; and a white box that says "Fortified with B complex and iron." In this study, the:

Accepted Answer

The study is examining the effect of package information on the way people rate breakfast cereal. The kind of cereal remains the same in all packages, so it is not confounded with the package information. However, the color of the box could potentially have an effect on how people rate the cereal, so it is a confounding variable that needs to be controlled for in the study. Therefore, the package information is confounded with the color of the box.

Question 5

Irene wants to examine the effect of a defendant's appearance on the judgment of guilt for a crime. She has participants read an identical account of the crime except for the defendant's appearance. A group of high school students receive the description of an attractive defendant, while a group of senior citizens receive the description of an unattractive defendant. Both groups are then asked to rate the defendant's guilt on a seven-point scale. A major cause for confusion in Madison's experiment is the _____.

Accepted Answer

The age of the participants is a potential confounding variable in this experiment because different age groups may have different attitudes and biases towards attractiveness and guilt. For example, the high school students may be more likely to be influenced by the appearance of the defendant due to their greater emphasis on physical appearance in their social lives, while senior citizens may be more likely to base their judgment on other factors such as the severity of the crime or the defendant's past criminal history. Therefore, the age variable may affect the results and make it difficult to draw clear conclusions about the effect of appearance on judgments of guilt.

Question 6

Mike wants to find out whether campers prefer cotton or nylon sleeping bags. He asks a group of girl campers to try both the nylon and cotton sleeping bags. The sleeping bags were rated for softness and warmth. What is the confounding variable in Mike's experiment?

Accepted Answer

The confounding variable in Mike's experiment is the gender of the camper. This is because the experiment only involved a group of girl campers, and gender may affect their preferences for sleeping bags. To eliminate this confounding variable, the experiment should involve both male and female campers. The other variables (material, softness, and warmth) are the independent variables that are being tested in the experiment.

Question 7

When the results of an experiment can confidently be attributed to the effect of the independent variable, the experiment is said to have:

Accepted Answer

Internal validity refers to the degree to which changes in the dependent variable can be confidently attributed to the manipulation of the independent variable. It is a measure of how well an experiment is designed and conducted, and how confident we can be that the observed effects are not due to other factors such as chance, bias or extraneous variables. Therefore, if the results of an experiment can be confidently attributed to the effect of the independent variable, it has high internal validity.

Question 8

Which of the following does NOT increase the likelihood of internal validity?

Accepted Answer

A pretest may actually create a bias in the study by sensitizing participants to the topic or measuring the variable of interest twice, which may affect their responses or behaviors during the actual study. Therefore, using a pretest may decrease internal validity, not increase it. On the other hand, control for extraneous variables, random assignment, and experimental control are all methods that can increase the likelihood of internal validity by reducing the possibility of alternative explanations for the results or confounding variables.

Question 9

When a confounding variable is present in an experiment, one cannot tell whether the results were due to the _____.

Accepted Answer

A confounding variable is an external factor other than the independent variable that might affect the outcome (dependent variable) of an experiment. Therefore, when a confounding variable is present, it becomes unclear whether the results are due to the independent variable or the confounding variable.

Question 10

Kalim wants to study the effectiveness of a new teaching method. He includes two teachers of a class in the experiment. One teacher uses the new method of teaching, and the other teacher uses the old method. At the end of the semester, he finds that students who were taught in the new way had higher grades than students taught in the old way. What is the confounding variable?

Accepted Answer

The confounding variable is the two teachers, as they may have different teaching styles or abilities which could affect the students' grades. Therefore, the difference in grades cannot solely be attributed to the teaching method.

Question 11

A confounding variable is problematic for an experimental design because it:

Accepted Answer

Confounding variables introduce alternative explanations for the results, making it difficult to determine if the independent variable caused the observed changes in the dependent variable or if another variable (the confounding variable) was responsible. This reduces the internal validity of the experiment.

Question 12

To study the effect of the type of stimulus on memory recall, Zhong subjects participants to either an auditory or visual presentation of a poem. After the presentation, the participants are asked to answer several questions about the poem. Which type of experimental design has Zhong employed?

Accepted Answer

Zhong's study does not mention a pretest or a comparison between pretest and posttest results; it only involves testing participants after they have been exposed to the stimulus (either auditory or visual), making it a posttest-only design.

Question 13

A researcher can claim that the independent variable caused the results only by:

Accepted Answer

By eliminating competing, alternative explanations, the researcher can be confident that the changes in the dependent variable were indeed caused by the manipulation of the independent variable. This is a crucial aspect of establishing causality in experimental research.

Question 14

A(n) _____ variable is a variable that varies along with the independent variable.

Accepted Answer

A confounding variable is one that varies along with the independent variable, potentially affecting the outcome of an experiment and making it difficult to determine the true effect of the independent variable.

Question 15

An experiment can be assumed to have internal validity if:

Accepted Answer

Random assignment and experimental control are essential components of an experiment's internal validity because they help to eliminate the influence of extraneous variables, making it more likely that the effect observed in the dependent variable is due to the manipulation of the independent variable. The validity of the dependent variable and the presence of confounding variables are also important considerations, but they alone are not sufficient to ensure internal validity. The strength of the manipulation is also not a definitive factor in determining internal validity.

Question 16

If the two groups involved in an experiment are not equivalent, _____.

Accepted Answer

If the two groups involved in an experiment are not equivalent, it means they have differences in characteristics that could affect the outcome of the experiment. In this case, it cannot be ascertained that the independent variable caused the results because other factors may have influenced the result as well. This reduces the experiment's internal validity, making it harder to draw reliable conclusions from the study.

Question 17

Good experimental design requires eliminating possible _____ variables that could result in alternative explanations.

Accepted Answer

Confounding variables are extraneous factors that can influence the relationship between the independent and dependent variables, making it difficult to determine whether the observed effects are due to the independent variable or some other factor. Therefore, it is important to eliminate or control for confounding variables in experimental design. Dependent and independent variables are not relevant to eliminating alternative explanations, and "valid" is not a type of variable.

Question 18

To achieve internal validity, a researcher must design and conduct experiments where only the _____ variable can be the cause of the results.

Accepted Answer

To achieve internal validity, researchers must carefully control all variables except for the independent variable, which is manipulated to examine its effects on the dependent variable. Confounding variables, which are extraneous variables that vary systematically with the independent variable, can threaten internal validity by providing alternative explanations for the observed results. Therefore, they must be eliminated or controlled to ensure that only the independent variable can be the cause of the results. The criterion variable is a variable that measures the outcome or effect of interest, but it is not relevant to the question of internal validity.

Question 19

When testing the effect of noise on the performance of a task, Marco tests half the participants in a cool, quiet room and the other half in a hot, noisy room. In this case, what confounding variable has Marco failed to eliminate?

Accepted Answer

Marco has failed to eliminate the confounding variable of room temperature. Since half the participants were tested in a cool room and the other half in a hot room, any differences in performance between the two groups could be due to the temperature difference rather than the noise level. To eliminate this confounding variable, all participants should be tested in the same temperature conditions.

Question 20

When a confounding variable is present in an experiment, _____.

Accepted Answer

Confounding variables are extraneous factors that can affect the outcome of an experiment, making it difficult to determine whether the independent variable or the confounding variable caused the observed effect. As a result, the internal validity of the experiment is challenged because it is unclear whether the experiment actually tested what it set out to test.

Quiz 8: Experimental Design