12.4:
Experimental Designs
Experimental studies are used to examine causal relationships between variables.
Suppose researchers are interested to know whether caffeinated drinks affect short-term memory.
So, how is this experiment designed to test the hypothesis?
Pre-experimental design is one of the basic types of experimental design, which involves observing the participants after some intervention. The memory tests are conducted before and after consuming caffeinated beverages, and inferences are drawn.
In the true experimental design, the samples are randomly divided into two groups, and memory tests are conducted. One group is allowed to drink the caffeinated drink, and another acts as a control group, consuming only decaffeinated beverages. After both groups have consumed their beverages, memory tests are conducted to draw inferences.
A quasi-experimental design is similar to true-experimental design, except that the samples are not randomly assigned to groups. Instead, they are free to choose either caffeinated or decaffeinated beverages.
After examining the memory scores, the researcher can draw inferences about the effect of caffeinated drinks on memory.
12.4:
Experimental Designs
An experimental design is a systematic process that allows researchers to evaluate the relationship between dependent and independent variables. There are three widely used types of experimental design – pre-experimental design, true experimental design, and quasi-experimental design. In pre-experimental design, the researcher compares the data before and after some interventions or treatments. The true-experimental design has more than one purposefully created group, a commonly measured outcome, and a random assignment. Here, subjects are divided into control and test groups. The control is maintained throughout the experiment without any treatment. The data from test group is then compared with control group to understand the baseline response and validate the treatment. The Quasi-experimental design is typically used in cases where random assignment is impractical.