Friday 27 April 2012

Sta630 GDB

True experimental design is considered to be more effective than quasi experimental design. Discuss validity of this statement with special emphasis on social research.
True Experimental Design:
A true experimental design is one in which the researcher manipulates the Independent Variable (or variables) to observe its effect on some behavior or cognitive process (the dependent variable) while using random assignment of participants to groups in order to control external factors from influencing the results. Without both manipulation of the IV and random assignment of participants, you do not have a true experimental design and, as a result, can't establish cause and effect.
Quasi Experimental Design:
This is one type of experimental design that is very similar to the True Experimental Design with one key difference. If you recall, for an experimental design to be classified as a True Experimental Design, it must meet two criteria;
1) Random assignment of participants to groups,
2) Manipulation of an internal variable
A Quasi- Experimental Design is exactly the same EXCEPT that there is no random assignment of participants to groups. That is the only difference between the two types of designs, but it is a very important difference. Without both random assignment and manipulation of an IV, a researcher can't make cause and effect conclusions. Sometimes it just is not possible to randomly assign participants to groups. An example of a quasi-experimental design would be a study in which you examine the effects of smoking on respiratory functioning. You might have people who smoke 1 pack a day and 2 packs a day smokers, but you can't really assign them into these groups (is it ethical to make people who smoke 1 pack a day now smoke 2?) You would then run your study, but when you make conclusions, you can't make any cause and effect conclusions.


By Hafiz Zeeshan

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