Experimental Studies (psychology - notes)

Experimental Studies  -  Cause and effect relationships are explored in experimental research.  The manipulation of one variable while keeping the others constant, may show that the experimental variable (or treatment), has an effect or it does not.

Steps in Experimental Designs:
1.  Identify variables:  The independent and dependant variables must be identified and controlled.
2.  After identification of variables, subjects must be assigned randomly to either the experimental group which receives the independent variable or the control group..which does not receive the independent or treatment variable.  The control group is used as a base of comparison....How did those subjects respond without the treatment?  Did the treatment in the experimental group influence the outcome measure or the dependent variable.
3.  Validity  and psychological research:  Random assignment gives all participants an equal chance of being assigned to experimental or control groups.  It permits the differences in subject characteristics to be evenly distributed by chance so that the experimental and control groups are as equal as possible in every way except in terms of the "treatment" or independent variable.  Thus, internal validity is assured and differences between the groups on the outcome or dependent variable measure can be confidentiality attributed to the treatment variable rather than to subject characteristics such as age, intelligence, education, socio-economic class; gender.
4.  Natural experiments:  these involve studying groups which naturally divide along some variable such as education or income or disease.  Thus, one group of people with formal education are compared to another group without formal education.

cont.....