Experimental Design Practice and Quiz

Explain the reason why random sampling is preferred in psychological studies.

(Sample response) Random sampling is preferred in psychological studies because it increases the generalizability of a study. A randomly generated sample is less influenced by any researcher bias since the researcher is not selecting participants directly. Since every member of a population has an equal chance to be selected in a random sample, it is more likely that the sample can be generalized back to the target population because the members of the sample are more likely to be representative of the population as a whole.

Compare and contrast extraneous variables with confounding variables.

(Sample response) Both types of variables have the potential to interfere with the relationship between the independent and dependent variable. Extraneous variables aren't included in the study but can still influence the results of the study if unaccounted for or if not controlled. Confounding variables interfere with study results due to having a connection with the independent variable that is not easy to separate or distinguish. A confounding variable can be considered a type of extraneous variable.

Describe the difference between convenience sampling and quota sampling.

(Sample response) Convenience sampling is based on the availability of participants or volunteers, and quota sampling is based on selecting participants from specific groups to make sure each group is properly represented for the study.

What is the difference between an independent and a dependent variable?

(Sample response) The difference between an independent variable and a dependent variable in an experiment is that the independent variable is the one that the researcher will change or alter in order to test the effects of the change on the dependent variable. The purpose of the experiment is to observe the relationship between changes in the independent variable and changes in the dependent variable. If the dependent variable changes as a result of the changes in the independent variable then the researcher knows that the two variable has a relationship.

What is the difference between the control group and the experimental group in an experimental study?

(Sample response) The difference in the control and experimental groups is the application of the independent variable. The experimental group has the independent variable altered or manipulated to test the effects on the dependent variable so the researcher can observe the effects of this change. In the control group, the independent variable is not applied to them. This group serves as a group for the researchers to compare the experimental group to in order to see if any changes that occur in the experimental group is really due to the manipulation of the independent variable.

Which of the following statements concerning the sample size of an experiment is not accurate? A. A smaller sample size decreases confidence in the accuracy of a study. B. A larger sample increases confidence in the accuracy of a study. C. A smaller sample size increases generalizability of a study D. A larger sample increases generalizability of a study.

C

Read the hypothesis below and answer the question that follows. Individuals who smoke will have a higher frequency of developing cancer later in life. Which of the following would not be a potential extraneous variable for the stated hypothesis? A. the occurrence of lung cancer in subjects B. exposure to secondhand smoke C. the amount of cigarettes smoked per day by subject D. the number of years as a smoker

A

Which of the following is a disadvantage of conducting a laboratory experiment? A. Cause-and-effect relationships are easier to determine in laboratory experiments. B. Laboratory experiments do not generally reflect real-life circumstances. C. There is more objectivity in measuring the dependent variable in laboratory experiments. D. Replicating the study is difficult for laboratory experiments.

B

Which of the following statements about extraneous variables is not accurate? A. An extraneous variable can also be a confounding variable. B. An extraneous variable clarifies the relationship between the independent and dependent variables. C. An extraneous variable can alter the results of an experiment in an undesired way. D. An extraneous variable cannot be the same as an independent variable.

B

Both the experimental group and the control group are exposed to the same __________. A. type of treatment B. independent variable C. confounding variables D. placebo treatment

C

Which is the fairest way to take a representative sample from a population? A. choosing participants who will ensure that study results will support the hypothesis B. carefully selecting specific subjects who meet one's criteria from the population C. ensuring that every subject in the population has an equal chance to be selected D. using a survey to screen out participants who may interfere with other subjects

C

Everyday occurrences, such as identifying criminals in police lineups, can be improved by using psychological experimental procedures, such as __________. A. single-blind procedures B. simultaneous lineups C. experimental design D. double-blind procedures

D

Playing video games will improve individual spatial skills. What is the dependent variable in the experiment? A. playing video games B. type of subjects C. type of video game D. spatial skills

D

In a single-blind study, neither the researchers or the participants are aware of group assignments.

F

One of the purposes of an experiment is to determine whether the dependent variable affects the independent variable.

F

A well-designed experiment can be replicated by others.

T

Convenience sampling can produce biased research results.

T

Understanding the effect of any confounding variables on the dependent variable is important to the outcome of an experiment.

T

Which of the following is an example of convenience sampling?

a dentist surveying patients about toothpaste preference

The control group in an experimental study will __________.

receive no treatment during the experiment