EXPERIMENTAL RESEARCH

Created by: Professor Hokerson

American River College

Last Updated: Spring 2013

Module A Lesson 2 Tutorial

USING THIS TUTORIAL

Use the navigation buttons across the bottom of the screen.

Click on hyperlinks when prompted

Have fun and learn!

TABLE OF CONTENTS

Objectives Module A Objectives #12 - 13

Action Items A Comparison Experimental Research Design

Independent Variable Dependent Variable Creating Groups Experiments

Research Examples Identifying Research Examples

Conclusions

MODULE A OBJECTIVES

By the end of this tutorial you will be able to…

# 12 – Identify the key distinction between descriptive and experimental research.

#13 – Explain the function of the dependent variable, independent variable, control group, and experimental group in the experimental method.

ACTION ITEMS

A COMPARISON

“Strategies for observing and describing behavior”(Hockenbury and Hockenbury, 2013)

Surveys Interviews Case Studies Naturalistic Observations Correlational

Each strategy has its own strengths and weaknesses!

“Method used to demonstrate a cause-and-effect relationship between changes in one variable and the effect that is produced on another variable”(Hockenbury and Hockenbury, 2013)

There is only one way to do an experiment!

Experiments also have strengths and weaknesses!

Descriptive Methods Experimental Method

EXPERIMENTAL RESEARCH DESIGN

Read: Chapter 1 – The Experimental Method (pages 27 – 33)

Researchers choose this method for one reason… To show cause – and – effect!

Experiments must have all these components: Independent Variable Dependent Variable Experimental Group Control Group

THE INDEPENDENT VARIABLE

A is the variable that will produce a change in B.

Definition: variable that is intentionally manipulated by the researchers It is the focus of the study

There must be an independent variable or it cannot be an experiment. Remember that this method attempts to describe a causal relationship between two (or more) variables.

Tip! An experiment can produce two results: There is a causal relationship (A did change B) There is no causal relationship (A did not change B)

THE DEPENDENT VARIABLE

A is the variable that will produce a change in B.

Definition: variable that is measured in response to the independent variable

An experiment cannot determine the effect of Variable A if its effects are not measured. Therefore, B (the dependent variable) measures those effects.

Tip! Dependent variables look a lot like descriptive methods: Surveys and questionnaires Behaviors that are observed and recorded Computer generated activities and games

CREATING GROUPS

To conclude cause-and-effect the researcher must expose some of the subjects to the independent variable

The researcher also needs to have a group of subjects that are not exposed to the independent variable

This is the manipulation!

Caveat: The simplest design has 1 experimental group and 1 control group, but there are many studies in which there are more than 2 groups!

EXPERIMENTS

Subjects are randomly assigned into either the control or experimental group.

The experimental groupreceives the IV…

…the control group proceeds directlyto the dependent variable OR receivesa placebo first.

Both groups complete the dependent variable.

Tip! If you cannot find these 4 components then you are reading descriptive research and can never, ever, ever conclude cause!

Experimental Group

Independent Variable

Dependent Variable

Control Group

Subjects

RESEARCH EXAMPLES

Research Examples

1. A study reported that babies and infants that watch programs geared toward enhancing intelligence use fewer words than their non-program watching cohorts.

2. A longitudinal study reported that factors such as motivation, creativity, and willingness to work hard are predictors of academic success.

3. A study reported that antidepressant use by adolescents can increase the risk of suicide.

Question: How did they arrive at these conclusions? Are they descriptive or do they conclude cause-and-effect?

IDENTIFYING RESEARCH METHODS

Question: How do you know if what you are reading is an experiment or descriptive research?

Tip: Decision Making Tree1. Do any of the conclusions say “cause”?

2. Are the subjects intentionally split into groups?

3. Do the subjects all do the same thing?

Practice: Complete the Research Examples Worksheet to practice differentiating between descriptive and experimental research.

CONCLUSIONS

Only an experiment can conclude cause-and-effect. Researchers intentionally manipulate these studies.

Experiments are highly controlled. Subjects are randomly assigned into different groups. Experiments are often conducted in labs or other unnatural

settings.

You should always walk away from research with more questions than answers. How can the results apply in other settings? Who were the subjects? Can any other variables explain the results?

MODULE A OBJECTIVES

After completing this tutorial you should be able to…

# 12 – Identify the key distinction between descriptive and experimental research.

#13 – Explain the function of the dependent variable, independent variable, control group, and experimental group in the experimental method.