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Ch 10: Internal Validity in Research

About This Chapter

Watch online video lessons and learn about internal validity in research. Take the quizzes that follow each lesson to test your knowledge of the related concepts.

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

VideoObjective
What is Internal Validity in Research? - Definition & ExamplesDefine and discuss internal validity.
Extraneous & Confounding Variables: Differences & ExamplesDifferentiate between extraneous and confounding variables.
Physical Variables that Affect Internal ValidityLearn about various physical variables that affect internal validity.
Researcher Variables that Affect Internal ValidityExplore various researcher variables that affect internal validity.
Participant Variables that Affect Internal ValidityExamine various participant variables that affect internal validity.
Threats to Internal Validity I: History, Instrumentation, Maturation & SelectionExplain 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 MethodsExplain how extraneous variables can be controlled through single blind, double blind and placebo methods.

9 Lessons in Chapter 10: Internal Validity in Research
What is Internal Validity in Research? - Definition & Examples

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.

Extraneous & Confounding Variables: Differences & Examples

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.

Physical Variables that Affect Internal Validity

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.

Researcher Variables that Affect Internal Validity

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.

Participant Variables that Affect Internal Validity

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.

Threats to Internal Validity I: History, Instrumentation & Subject Mortality

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.

Threats to Internal Validity II: Statistical Regression & Testing

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.

Threats to Internal Validity III: Selection, Maturation & Selection Interaction

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.

Controlling for Extraneous Variables: Single Blind, Double Blind & Placebo Methods

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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