The patient then waited through an extended period for healing. Then, in a surgery similar to those done to create vaginas for intersexed patients, surgeons constructed the patient's vagina by using skin grafts taken from her thighs or buttocks (Christine's vaginoplasty surgery was in 1954).
Experimental and quasi-experimental research designs. Ph.D. In an experimental design, subjects are randomly assigned to groups for different levels of treatment (or no treatment, i.e., the control group). In a quasi-experimental design, subjects are not randomly assigned to treatment; there is no randomization. Random assignments of subjects helps control for participant differences, one of the main sources of threats to internal validity of a research study.
Experiments can be done in the field or in a laboratory. They can involve human or animal subjects. What distinguishes the type of experiment is the degree to which the experimenter can assign subjects to conditions. Three types are described here: True, Quasi- and Single-subject experiments. In a true experiment, subjects are randomly assigned to the treatment conditions (levels of the independent variable). The only differences in the groups would be due to chance. True experiments are excellent for showing a cause-and-effect relationship.