Please help with some examples and information on the following - What are some major differences between experimental and quasi-experimental designs? What different types of manipulations can be used? Any sources would be helpful as this is just one minor part for additional research.
The key difference between experimental and quasi-experimental designs is the lack of control conditions in the latter.
Let's say I'm trying to study the effects of drug X on neurons' ability to survive. I could easily test this by applying drug X into a well of neurons, stir the media to make sure the drug diffuses across the well and see if I observe any difference in the number of neurons, or the morphology of the neurons in that same well before and after treatment. Keep in mind that although I would have some idea of what drug X might do to the neurons, it does not account for certain actions the experimenter has introduced, such as stirring the media, or adding extra volume ...
The solution discusses experimental and quasi-experimental designs.