Experimental research is concerned with control of independent variables to determine their impact on dependent variables.

Advantages: Cause and effect can be established.

Control of conditions----environmental control

Control of variables---reduction of competing explanation

The attempt is made to control competing explanations, the experimenter tries to isolate the effect of one or more variables.

Statistical control:

Disadvantages

Research takes place in artificial settings.

Subjects are passive reactors.

External validity issues

Experimental and Nonexperimental design

Experimental:

Random assignment

Allows for causal relationships.

Nonexperimental

Establishes that a relationship exists.

Non random assignment.

Three types of experimental and non experimental design

One shot case study.

X 0

One group pretest posttest desing

O X O

Static Group Comparison

X O

O

True Experimental

The Pretest-Posttest Control Group

Design

R O1 X O2

R O3 O4

Mutiple Group Posttest Design

X O

X O

Mutiple Group Pretest Posttest

O X O

O X O

Solomon Four Group Design

R O X O

R O O

R X O

R O

Quasi-Experiments

Time Series:

O O O O XO O O O

Equivalent Time Sampels Design

X 1O X0O X1O X0O

Nonequivalent Control Group Design

O O