True Experimental Design
TRUE EXPERIMENTAL DESIGN
DEFINED:
This category of design includes more than one
purposely created group, common measured outcome/s, and random assignment.
It is regarded as the most accurate form of experimental approach.
It proves or disproves a hypothesis mathematically, with statistical analysis.
Criteria for an experimental design to fit as a true experimental design:
The sample groups must be assigned randomly.
There must be a viable control group.
Only one variable can be manipulated and tested.
The tested subjects must be randomly assigned to
either control or experimental groups.
ADVANTAGES:
The results of a true experimental design can be
statistically analyzed and so there can be little argument about the results.
It is easier to replicate the experiment and validate the results. It is easier to manipulate one variable. It usually gives a yes or no answer.
DISADVANTAGES:
Less external validity (not like real world conditions).
Not very practical (too difficult and expensive)
EXAMPLE
In order to study the effects of a new headache medication, researchers select 80 subjects at random.
They divide the subjects into two groups of 40 and one group is given a sugar pill, and the other is given the new headache medicine.
The researchers give the subjects the treatments for 3 weeks. After the designated time period, the researchers count the number of headaches for each subject.
The researchers then calculate the t-test and p value to be .03, indicating that there is a significant difference between the sugar pill group and the treatment group.
Therefore, the researchers conclude that the new headache medication is effective at treating headaches.
Why is it considered to be a TRUE
EXPERIMENTAL DESIGN?
The sample groups must be assigned randomly.
…researchers select 80 subjects at random.
There must be a viable control group.
… one group is given a sugar
DEFINED:
This category of design includes more than one
purposely created group, common measured outcome/s, and random assignment.
It is regarded as the most accurate form of experimental approach.
It proves or disproves a hypothesis mathematically, with statistical analysis.
Criteria for an experimental design to fit as a true experimental design:
The sample groups must be assigned randomly.
There must be a viable control group.
Only one variable can be manipulated and tested.
The tested subjects must be randomly assigned to
either control or experimental groups.
ADVANTAGES:
The results of a true experimental design can be
statistically analyzed and so there can be little argument about the results.
It is easier to replicate the experiment and validate the results. It is easier to manipulate one variable. It usually gives a yes or no answer.
DISADVANTAGES:
Less external validity (not like real world conditions).
Not very practical (too difficult and expensive)
EXAMPLE
In order to study the effects of a new headache medication, researchers select 80 subjects at random.
They divide the subjects into two groups of 40 and one group is given a sugar pill, and the other is given the new headache medicine.
The researchers give the subjects the treatments for 3 weeks. After the designated time period, the researchers count the number of headaches for each subject.
The researchers then calculate the t-test and p value to be .03, indicating that there is a significant difference between the sugar pill group and the treatment group.
Therefore, the researchers conclude that the new headache medication is effective at treating headaches.
Why is it considered to be a TRUE
EXPERIMENTAL DESIGN?
The sample groups must be assigned randomly.
…researchers select 80 subjects at random.
There must be a viable control group.
… one group is given a sugar