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Behavioral Research

Chapter Four Studying Behavior

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Introduction

• Examine the basic issues and concepts

necessary for understanding behavioral research.

• Look at the nature of variables, including

measurement, types of relationships, and general methods for studying these relationships.

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Variable- (def) any event, situation, behavior or individual characteristic that has two or more levels or values on which they can vary. Four General Categories of Variables

• Response Variables
• Situational Variables
• Participant (Subject) Variables
• Mediating Variables

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Operational Definitions of Variables

• perationally definition  defines a

concept by specifying precisely how the concept is measured or manipulated in a particular study.

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How does it help us to operationally define our variables?

• Defining an abstract term helps you to

determine if your study (your focus) is too vague or not.

• Having operationally defined our

variables also helps us to communicate

• ur ideas to others .

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Relationships Between Variables

Four most common relationships found in research are:

• Positive liner relationship- increases in the values of one

variable are accompanied by increases in the values of the second variable.

• Negative linear relationship- Increases in the values of one

variable are accompanied by decreases in the values of the

• ther variable.
• Curvilinear relationship Increases in the values of one variable

are accompanied by both increases and decreases in the values of other variables.

• No relationship- When there is no relationship between the two

variables the graph is a straight line.

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Correlational coefficient

• (def) a numerical index of the strength of the

relationship between variables.

• When variables are highly correlated, this

indicates there is little deviation in the general pattern of the data.

• When two variables are weakly correlated,

there are either many Participants who deviate from the general pattern of the data or the two variables don’t effect each other that strongly.

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Nonexperimental vs. Experimental Methods

Nonexperimental method  relationships are studied by making observations or measures of the variables of interest . When the two variables vary together---we say that they are correlated.  While we can say that there is a relationship between the two variables, we cannot say we can determine causality.  CORRELATION DOES NOT IMPLY CAUSATION!!

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Problems with Non-Experimental Method

• Direction----cannot tell which variable

causes the other.

• Third Variable problem: There may be a

relationship between the two variables because some other variable causes both. (also called confounding variables).

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Experimental method

• Involves direct manipulation and control of variables.
• The researcher manipulates the variable of interest

and then observes (measures) the response.

• Because one variable is manipulated while the other is

measured, researchers can now comment about the direction of cause and effect.

• The experimental method helps to eliminate the

ambiguity found in the results

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Extraneous variables  variable that interferes with the results, making it impossible for the researcher to draw meaningful conclusions about the effect of the variables. Experimental Control-with experimental control all extraneous variables are kept constant, and therefore cannot be responsible for the results of the experiment. Randomization- The experimental method ensures that extraneous variables, in which control would be difficult, are equalized through random assignment.

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Independent and Dependent Variables

• Independent variable  what’s

manipulated by the experimenter—the variable that is considered to be the cause.

• Dependent variables  Ps’ response, or

what is measured—the variable that is the effect of the dependent variable.

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Two Kinds of Independent Variables

• Manipulated I.V.
• Non-Manipulated I.V.
• Constant  a variable that is held

constant, in order to prevent it from varying, and possibly affecting the

• utcome of the experiment.

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Evaluating Research-Three Validities

• Construct Validity 
• Internal validity 
• External validity 

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