CHAPTER 10
Independent and Dependent Variables
IV = the CAUSE factor and a cause is something that makes something else happen.
DV = the EFFECT factor and an effect is what happens as a result of the cause.
MV = the second independent variable that is included because it is believed to have a significant contributory effect on the originally stated IV–DV relationship.
Extraneous Variable
defined as the factors that might disturb the relationship between IV & DV
Intervening variable
defined as the factor which theoretically affects the observed phenomenon but cannot be seen, measured or manipulated.
What is Experimentation?
A set up to examine the possible cause and effect relationship among variables
without necessarily trying to establish if one variable causes the other
Conditions to Establish Cause and Effect Relationship
Both X and Y should covary
X (the presumed cause factor) should precede Y (the presumed effect factor).
No other factor should possibly cause the change in the dependent variable Y
How to do Experimentation?
Stage 1: controlling the contaminating factors
Stage 2: manipulating the IV and
Stage 3: measuring the change in DV
Field Experiment vs Lab Experiment
Field experiment
an experiment done in the natural environment in which work goes on as usual, but treatments are given to one or more groups
Lab experiment
the controls and manipulation are done in an artificial setting, where the causal effects relationship can be tested
Methods of Controlling Contaminating Factors
Matching Group Method
try to match the various groups by picking the confounding characteristics and deliberatively spreading them across the groups
Randomization Method
we randomly choose the subjects so that each subject has a known and equal chance of being assigned to any of the groups
Validity In Experimentation
internally valid to the extent that it shows a cause-effect relationship between IV & DV
refers to the extent to which the results of a study can be generalized or extended to others
Factors Affecting Internal Validity
History, Maturation Effect, Testing Effect, Instrumentation Effect, Selection Bias Effect, Mortality Effect and Experimenter Bias
Factors Affecting External Validity
Reactive Effect of Testing
Selection-treatment Interaction
Reactive Effects of Experimental Arrangements
Multiple-treatment Interference
Types of Experimental Design
Pre-experimental design
The one-shot case study
One group pre-test post-test study
The static group comparison study