Quasi Experiments Overview

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Questions and Answers

What does regression to the mean imply about extreme outcomes over time?

They are influenced only by external variables.

They become more extreme due to consistent factors.

They get less extreme as random combinations of factors diminish. (correct)

They remain constant and do not change.

Which situation is a clear example of attrition threat?

Changes in results because of repeated testing.

Participants improving due to expectation.

Individuals consistently leaving the study over time. (correct)

Variations in measures used in the study.

How can testing and instrument threats affect internal validity?

They enhance the effectiveness of placebo treatments.

They are caused by external events unrelated to the study.

They lead to a placebo effect in participants.

They can cause participant behavior to change due to prior testing. (correct)

What is observer bias primarily concerned with in the context of a study?

Who conducted the measurement and the study's level of blinding. Signup and view all the answers

Demand characteristics are best described as:

When participants guess the study's purpose and alter their behavior. Signup and view all the answers

Which aspect enhances external validity in studies?

Utilizing diverse real-world opportunities for research. Signup and view all the answers

In research, what is the primary concern of construct validity?

The appropriateness of the variables measured and manipulated. Signup and view all the answers

What does statistical validity primarily evaluate in a study?

The magnitude of the observed group differences. Signup and view all the answers

What is a key characteristic of a quasi-experiment?

The inability to randomly assign participants to independent variable conditions Signup and view all the answers

In the context of quasi-experiments, what is meant by 'selection effects'?

Differences in participant characteristics at different independent variable levels Signup and view all the answers

What does 'maturation threat' imply in a quasi-experimental design?

Changes occurring naturally over time that could affect results Signup and view all the answers

Which of the following is an example of a nonequivalent control group interrupted time-series design?

Examining suicide rates before and after a specific show aired Signup and view all the answers

Why are researchers limited in their ability to draw causal conclusions in quasi-experiments?

There may be uncontrolled confounding variables affecting outcomes Signup and view all the answers

What risk is associated with external historical events during a study?

Internal validity may be compromised due to uncontrolled variables Signup and view all the answers

In the context of the cosmetic surgery study, what does the term 'nonequivalent control group pretest/posttest design' refer to?

Pre-existing groups are used to measure differences before and after an intervention Signup and view all the answers

What phenomenon explains why many participants accept default options in organ donation?

Social pressure and perceived effortlessness of the default choice Signup and view all the answers

What is a primary concern when conducting quasi-experimental research?

Internal validity can be threatened by various confounding factors Signup and view all the answers

Study Notes

Quasi Experiments

Quasi experiments are similar to experiments but researchers lack full control
They may not be able to randomly assign participants to conditions
Researchers may rely on pre-existing groups or naturally occurring events

Examples of Quasi-Experiments

Organ Donation:
- Opt-in (people choose to donate) vs. opt-out (people must actively decline) methods
- Default options often influence decisions
Cosmetic Surgery:
- Researchers studied self-esteem after surgery
- Used a nonequivalent control group (participants not randomly assigned) to assess effectiveness
Shows and Suicide:
- Researchers evaluated suicide rates before and after a popular show (time-series design)
- Assessed impact of show content on suicide incidents

Internal Validity

The ability to draw causal conclusions from results
Researchers have limited control of independent variables in quasi-experiments

Threats to Internal Validity in Quasi-Experiments

Selection Effects: Participants in different groups may differ systematically before the study begins
Design Confounds: An uncontrolled variable influences the independent variable
Maturation: Participants change over time, independent from the treatment
History: External events influence the outcome
Regression to the Mean: Extreme scores tend to become less extreme over time
Attrition: Participants dropping out of a study
Testing: Participants may improve over repeated testing regardless of treatment
Instrumentation: Changes in measurement instruments may influence results
Observer Bias: Researchers' expectations might influence observations
Demand Characteristics: Participants adapt their behaviors based on study goals

Other Important Considerations

Placibo Effect: Participants improve due to belief in treatment effectiveness
External Validity: The ability to generalize findings to other situations and populations
Ethics: Researchers must consider ethical implications of quasi-experimental studies
Construct Validity: How well the study measures the intended variables
Statistical Validity: The importance of effect size in quasi-experiments
Quasi-independent Variables: These are measured rather than manipulated (e.g., age, gender)

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Description

This quiz explores the concept of quasi experiments in research methodology. It highlights their similarities to traditional experiments, the challenges with participant assignment, and various examples like organ donation and cosmetic surgery studies. Understand the implications of internal validity and factors that threaten it in quasiexperimental designs.