Question 1

What is the difference between true experimental designs and quasi-experimental designs?

Accepted Answer

The main difference between true experimental designs and quasi-experimental designs is that true experimental designs use random assignment, whereas quasi-experimental designs do not. Random assignment is a crucial component for making causal inferences about the relationship between independent and dependent variables. Quasi-experimental designs lack random assignment, which makes it difficult to establish cause and effect relationships. While both true experimental and quasi-experimental designs may use control groups, this is not the defining characteristic that distinguishes them from each other.

Question 2

A quasi-experimental design attempts to:

Accepted Answer

A quasi-experimental design attempts to approximate the control features of true experiments, but it may not be possible to completely control all extraneous variables. Thus, it is an approximation of a true experimental design rather than a true experimental design itself.

Question 3

When asked if he would like to have some fruits along with his breakfast, Milo declines. He then attends an all-day presentation on the nutritional benefits of eating fruits. At the end of the presentation, Milo is again offered some fruits to eat and he accepts. What effect may be responsible for the change in Milo's response?

Accepted Answer

Milo's change in response may be due to maturation, as the presentation on the nutritional benefits of eating fruits may have increased his knowledge and understanding of the importance of fruits in a healthy diet.

Question 4

A researcher asks students to record in a journal the emotions they experience every hour. She finds that over time, the descriptions become shorter and less detailed. What may be responsible for this change in performance?

Accepted Answer

Instrument decay refers to the gradual deterioration of the assessment tool or instrument over time. In this scenario, the journal may have become less engaging or the students may have become less diligent in recording their emotions, leading to shorter and less detailed descriptions.

Question 5

If exposure to an earlier assessment affects behavior when a participant is assessed a second time, which of the following types of effects might the researcher suspect is the cause?

Accepted Answer

The scenario described is an example of the testing effect, which occurs when exposure to a test affects scores on a subsequent test. This could happen if participants remembered how they responded the first time and adjusted their behavior accordingly, even if the second assessment used different questions or stimuli. The other options do not seem to fit the scenario as well. History effects refer to external events that occur between assessments, instrument decay describes changes in the reliability or validity of a measure over time, and maturation refers to natural changes that might occur in participants (e.g., as they age) that could affect their performance on the second assessment.

Question 6

_____ designs address the need to study the effect of an independent variable in settings in which the control features of true experimental designs cannot be achieved.

Accepted Answer

Quasi-experimental designs are used when true experimental designs are not possible or ethical. They lack random assignment and control over extraneous variables, but still allow for the investigation of cause and effect relationships between independent and dependent variables. Single-case experimental, multiple baseline, and interrupted time series designs are all specific types of quasi-experimental designs.

Question 7

Dr. Jayden is studying the effect of exercise on cholesterol level. He first measures his patients' cholesterol level before recommending an exercise program and after one month of participating in an exercise program, he measures their cholesterol level again. What type of research design has Dr. Jayden employed?

Accepted Answer

Dr. Jayden has employed a one group pretest-posttest design as he is measuring the cholesterol levels of the same group before and after they participate in the exercise program.

Question 8

A researcher wants to study the effect of weather on college students' study habits. On a sunny day, the researcher sits in the quad and records the number of minutes of study per student. Identify the crucial element missing in this design.

Accepted Answer

The crucial element missing is a control group, which would allow the researcher to compare the study habits of students on sunny days to those on non-sunny days to accurately assess the effect of weather.

Question 9

Which of the following is a threat to the internal validity of studies using one-group pretest-posttest design?

Accepted Answer

One-group pretest-posttest design does not include a control group for comparison, making it vulnerable to statistical regression. This occurs when participants with extreme scores in the pretest tend to move toward the mean in the posttest, simply due to chance or natural random variation. This phenomenon can lead to an overestimation or underestimation of the treatment effect, impacting the internal validity of the study. Cohort effects (A), propensity score matching (C), and selection bias (D) are all potential threats to internal validity, but they are not specific to the one-group pretest-posttest design.

Question 10

A researcher wants to investigate the effect of weather on college students' study habits. On a sunny day, the researcher sits in the quad and records the number of minutes each student puts into studying. The researcher finds that the mean number of minutes of study is 39.8. This is an example of a:

Accepted Answer

This is an example of a one-shot case study as there is only one observation and no control group or pretest exists. The researcher is simply observing behavior on a single occasion.

Question 11

_____ in quasi-experimental designs is more difficult than in true experiments because quasi-experimental designs lack the important features of true experiments such as random assignment to conditions.

Accepted Answer

Causal inference is more difficult in quasi-experimental designs because they lack random assignment to conditions, which is a crucial element for establishing causality. Without random assignment, it is possible that pre-existing differences between groups (such as differences in personality or motivation) could be responsible for any observed differences in outcomes, rather than the experimental manipulation being studied.

Question 12

A researcher administers a reading test to a group of fourth graders at the beginning of the school year. During the year, the students receive an intensive program designed to improve reading skills. At the end of the year, the reading test is given again and a large improvement in test scores is discovered. Identify the type of study.

Accepted Answer

The study is a one-group pretest-posttest design because the same group of students is tested twice, once before and once after the implementation of the intensive reading program.

Question 13

In the context of one-group pretest-posttest design and the associated threats to internal validity, any changes that occur systematically over time are called _____ effects.

Accepted Answer

Maturation effects refer to changes that occur systematically over time due to natural development or aging of participants, which can affect the outcome of the study. Regression effects refer to statistical phenomenon where extreme scores on pretest tend to regress towards the mean on posttest. Testing effects refer to the impact of taking a pretest on subsequent performance, leading to inflated or deflated scores. History effects refer to external events that occur during the study period and may influence the outcome of the study.

Question 14

Events that occur between the first and second measurement period but are not part of the manipulation are called _____ effects.

Accepted Answer

History effects refer to external events that occur between the first and second measurement period but are not part of the manipulation. Maturation refers to changes within the participants themselves, such as physical or emotional growth, that occur naturally over time. Testing effects refer to the impact of simply taking the first measurement on subsequent responses. Cohort effects refer to differences in responses that are tied to characteristics of the participants' generation (e.g., millennials vs. baby boomers).

Question 15

At the beginning of the term, researchers measured the attitudes of students taking a class in cross-cultural communication. At the end of the term, the students' attitudes were measured again. This is an example of a(n) _____ design.

Accepted Answer

The given scenario is an example of a one-group pretest-posttest design. This is because the same group of students is being measured twice, once before the class and once after the class, with no other group to compare them to.

Question 16

A researcher assesses participants' attitude toward marijuana, presents them with a persuasive communication favoring liberalization of marijuana laws, and then reassesses their attitude toward the drug. However, between assessment 1 and assessment 2, the President also advocates liberalization of marijuana laws. If the researcher doesn't use a control group, any differences that he or she observes are likely to be caused by _____ effects.

Accepted Answer

The President advocating liberalization of marijuana laws is a historical event that could influence participants' attitudes, regardless of the persuasive communication presented by the researcher. Therefore, without a control group, any observed differences may be due to the influence of this external event, which is a history effect.

Question 17

In the context of one-group pretest-posttest design, testing effects occur when:

Accepted Answer

Testing effects refer to the changes in participant behavior due to the pretest itself. Simply taking a pretest can influence how participants respond on the posttest, which can affect the accuracy of the results. This is why it's important to minimize the effects of testing by using alternate forms of the test for the pretest and posttest, or by using a control group that does not take the pretest. Boredom or fatigue (B) may influence participant behavior, but this is not specific to the pretest and can occur during any phase of the study. Confounding events (C) can introduce extraneous variables that affect the results, but this is not related to testing effects. Finally, changes in the measuring instrument (D) are a form of instrumentation effects, which again are different from testing effects.

Question 18

A researcher pretests a group of participants to determine their attitudes toward the use of alternative energy sources to replace crude oil. The researcher then initiates a program to convince them that they should invest in such alternatives. During this time, the price of gasoline rises $.50 per gallon. At the end of the program, the researcher retests and finds that the participants are much more positive in their attitudes. What threat to internal validity most likely accounts for this change?

Accepted Answer

The rise in gasoline prices during the program could be a confounding factor that influenced the participants' attitudes, rather than the program itself. This is an example of the history threat to internal validity.

Question 19

In order to study the effects of watching violent programs on children's aggressiveness, a researcher observes children's behavior after they watch 30 minutes of violent programs on television. The researcher concludes that television violence causes aggressiveness. A problem in this research is that:

Accepted Answer

The absence of a control group makes it impossible to determine whether the children's aggressiveness was caused by the television violence or another variable.

Question 20

Ethan has developed a scale to measure a person's fear of earthquakes. After the occurrence of an earthquake, he surveys 1000 individuals and finds the mean score to be 7.8 out of a possible 10 (the higher the score, the greater the fear). Ethan concludes that fear increases after people experience an earthquake. This study is an example of a:

Accepted Answer

This study is an example of a one-shot case study design because there is no control group and only one measurement is taken after the earthquake has occurred. Therefore, it cannot be a true experiment, one group pretest-posttest design or control group design.

Quiz 11: Single-Case, Quasi-Experimental, and Developmental Research