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Ch 12: Experimental Design

About This Chapter

Use these video lessons to learn about types of experiment design as well as issues you may encounter in creating experiments. Each lesson is accompanied by a short multiple-choice quiz you can use to check your understanding of these research design topics.

Experimental Design - Chapter Summary and Learning Objectives

In this chapter, you'll learn about experimental design, one of the most important factors in scientific research. Instructors explain key aspects of experiment design, including how to achieve random assignment, what purpose control groups serve and why variables matter. This chapter is designed to teach you about topics including:

  • Between-subjects designs
  • The importance of random assignments
  • Group designs, including two-group and matched group design
  • Types of within-subjects designs

Video Objective
Between-Subjects Designs: Definition and Examples Define and discuss this type of design that tests two or more groups at the same time.
Random Assignment in Research: Definition and Importance Define and discuss random assignment, its importance and how it is accomplished.
What is a Control Group? - Definition and Use in Research Define and discuss control groups and the use of experimental groups and control groups in research designs.
Two-Group Experimental Designs: Definition and Examples Define and discuss the basic two-group experimental design in psychology research.
Matched Group Design: Definition and Examples Define and discuss matched group design and how it can test for extraneous variables.
Multiple Group Design: Definition and Examples Define and discuss multiple group design and the observation of an independent variable.
What is Factorial Design? - Definition and Examples Define and discuss factorial design and how researchers can study more than one independent variable at a time.
Factorial Design Variations Explain the different factorial designs and how researchers would use them.
Within-Subjects Designs: Definition, Types and Examples Define and discuss within-subjects designs, including one independent variable, multiple independent variables and mixed designs.
Carryover Effects and How They Can Be Controlled Through Counterbalancing Define and discuss carryover effects and how to control them.
Small n Designs: ABA and Multiple-Baseline Designs Explain small n designs and discuss ABA and multiple-baseline designs.

15 Lessons in Chapter 12: Experimental Design
Between-Subjects Designs: Definition & Examples

1. Between-Subjects Designs: Definition & Examples

Many times in research, a psychologist wants to look at two or more groups to see which condition works best. In this lesson, we'll look at some of the strengths and weaknesses of the between-subjects design and how to form equivalent groups.

Random Assignment in Research: Definition and Importance

2. Random Assignment in Research: Definition and Importance

In order to get the most accurate results, researchers must choose and assign their subjects in a random manner. In this lesson, we'll look at random assignment, random selection, and why they are important.

What is a Control Group? - Definition and Use in Research

3. What is a Control Group? - Definition and Use in Research

In research, many times a condition is compared to a group that doesn't receive treatment. In this lesson, we'll look at what a control group is and why it is important.

Two-Group Experimental Designs: Definition & Examples

4. Two-Group Experimental Designs: Definition & Examples

How does a researcher know if their treatment has an effect or not? In this lesson, we'll look at two-group experimental designs, contrast control and treatment groups, and examine random assignment and matched groups.

Matched-Group Design: Definition & Examples

5. Matched-Group Design: Definition & Examples

Choosing how to divide subjects into groups is a major part of experimental design. In this lesson, we'll look at a type of non-random assignment, matched-group design, and its strengths and limitations.

Multiple Group Design: Definition & Examples

6. Multiple Group Design: Definition & Examples

What happens when a researcher has many groups in their study? In this lesson, we'll look closer at multiple-group design, including multiple-group design with independent groups and multiple-group design with correlated groups.

What is Factorial Design? - Definition & Example

7. What is Factorial Design? - Definition & Example

The simplest studies involve one independent and one dependent variable. But what happens when a researcher wants to study more than one independent variable? In this lesson, we'll look closer at factorial design in research.

Factorial Design Variations

8. Factorial Design Variations

When a study has more than one factor, it is called a factorial design. In this lesson, we'll go through different variations on factorial designs, including those involving factor levels and those involving between- or within-groups measurement.

Interactions in Factorial Design

9. Interactions in Factorial Design

When a study has a factorial design, the two independent variables can interact with each other to affect the dependent variable. In this lesson, we'll look at what interactions are, what they look like, and what a crossover interaction is.

Main Effects in Factorial Design

10. Main Effects in Factorial Design

When you have more than one independent variable, sometimes you want to look at how they work independent of each other. In this lesson, we'll examine main effects in factorial design and how they differ from interactions.

Multivariate Experimental Design

11. Multivariate Experimental Design

Most research studies only have one dependent variable. But what if a researcher wants to study more than one dependent variable? In this lesson, we'll look at multivariate research designs and how they differ from factorial designs.

Within-Subject Designs: Definition, Types & Examples

12. Within-Subject Designs: Definition, Types & Examples

Sometimes a researcher wants to look at how each subject does at different points during a study. In this lesson, we'll look at some of the strengths and weaknesses of a within-subjects design and how to counterbalance subjects for a stronger study.

Carryover Effects & How They Can Be Controlled Through Counterbalancing

13. Carryover Effects & How They Can Be Controlled Through Counterbalancing

Within-subjects research has a lot of advantages, but one disadvantage is the possibility of carryover effects. In this lesson, we'll examine carryover effects and how they can be controlled through a counterbalanced design.

Small n Designs: ABA & Multiple-Baseline Designs

14. Small n Designs: ABA & Multiple-Baseline Designs

When planning a study, the size of the sample can influence the results of the study. To get around this, some researchers choose a research design specifically meant for small sample sizes. In this lesson, we'll look at some small 'n' designs.

Advantages & Disadvantages of Various Experimental Designs

15. Advantages & Disadvantages of Various Experimental Designs

There are many different options for researchers when deciding how to run a study. In this lesson, we'll look at some of the advantages and disadvantages of some common experimental designs.

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