About This Chapter
Internal Validity in Research - Chapter Summary and Learning Objectives
Internal validity is paramount in research. Researchers need to be sure their work hasn't been compromised by a physical variable, by a participant or by the researchers themselves. Through the brief video lessons in this chapter, you'll learn about extraneous and confounding variables in research as well as ways to control for extraneous variables. By the end of the chapter, you should be able to do the following:
- Explain how research bias, researcher personality and selection of subjects can affect internal validity
- Describe the effect of demand characteristics, volunteers, 'good subject' bias and social desirability on internal validity
- Identify various types of threats to internal validity, such as instrumentation, statistical regression and subject mortality
|What is Internal Validity in Research? - Definition & Examples||Define and discuss internal validity.|
|Extraneous & Confounding Variables: Differences & Examples||Differentiate between extraneous and confounding variables.|
|Physical Variables that Affect Internal Validity||Learn about various physical variables that affect internal validity.|
|Researcher Variables that Affect Internal Validity||Explore various researcher variables that affect internal validity.|
|Participant Variables that Affect Internal Validity||Examine various participant variables that affect internal validity.|
|Threats to Internal Validity I: History, Instrumentation, Maturation & Selection||Explain how history, instrumentation, maturation and selection can threaten internal validity.|
|Threats to Internal Validity II: Selection||Discuss how selection integration, statistical regression, subject mortality and testing can threaten internal validity.|
|Controlling for Extraneous Variables: Single Blind, Double Blind & Placebo Methods||Explain how extraneous variables can be controlled through single blind, double blind and placebo methods.|
1. What is Internal Validity in Research? - Definition & Examples
The purpose of most research is to show that one variable causes changes in another variable. But, what happens when other variables come into play? In this lesson, we'll explore the definition, importance and threats to internal validity.
2. Extraneous & Confounding Variables: Differences & Examples
What happens when something other than your independent variable is influencing the outcome of your study? In this lesson, we'll look at two types of variables that can affect an experiment: extraneous and confounding variables.
3. Physical Variables that Affect Internal Validity
How might a researcher accidentally mess up the results of his or her study? In this lesson, we'll look at one type of extraneous variable that can change experimental results - physical or situational variables.
4. Researcher Variables that Affect Internal Validity
Scientists want only the independent variable to affect the outcome of their studies, but sometimes it is the things they do themselves that change the outcome. We'll look at three common researcher-related variables: researcher bias, selection bias, and researcher personality in this lesson.
5. Participant Variables that Affect Internal Validity
Sometimes, participants in an experiment can change the outcome. In this lesson, we'll look at some of the extraneous variables caused by participants: self-selection bias, demand characteristics, and good-subject bias.
6. Threats to Internal Validity I: History, Instrumentation & Subject Mortality
In research, there are many things besides the independent variable that can affect the dependent variable. In this lesson, we'll look at three of those things - history, mortality, and instrumentation - and what they mean to research.
7. Threats to Internal Validity II: Statistical Regression & Testing
If you're doing research, how do you know if one thing causes another? In this lesson, we'll look at some common threats to the internal validity of experiments, including testing effects and regression to the mean.
8. Threats to Internal Validity III: Selection, Maturation & Selection Interaction
A major goal of research is to prove that one thing causes another thing. But there are some hurdles to being able to say that. In this lesson, we'll look at three threats to internal validity: selection, maturation, and selection interaction.
9. Controlling for Extraneous Variables: Single Blind, Double Blind & Placebo Methods
Sometimes researchers are confronted with extraneous factors that affect the outcome of their studies. In this lesson, we'll look at ways to control for these extraneous variables, including single-blind and double-blind studies and placebos.
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Other chapters within the Psychology 105: Research Methods in Psychology course
- Introduction to Research Methods
- Principles of Ethical Research
- Setting Up the Research Study
- Data Collection Techniques in Psychology
- Nonexperimental Research
- Qualitative Research Methods and Design
- Quasi-Experimental Research
- Sampling and Generalization
- Measurement in Research
- External Validity
- Experimental Design
- Descriptive Statistics in Psychology
- Inferential Statistics in Psychology
- Evaluating Research Findings
- Studying for Psychology 105