Why do true experiments have the most control?
• All experiments must have at least two levels (e.g. 100mg vs. 200mg of caffeine) or treatment groups. • The degree to which these groups are equivalent, with the exception of the treatment they receive, reflects the amount of control the experiment has. In other words, confounding variables have been controlled. • Random assignment is the most common way to equate groups before they receive any treatment, which is possible with the true experiment. • For example, it is possible to randomly assign participants to receive either 100mg of caffeine or 200mg of caffeine. In theory, the random assignment equates the two groups with respect to variables that may affect the D.V. C. Why do quasi-experiments lack the control of the true experiment? • Quasi experimental designs use intact groups; therefore, random assignment is not possible. • For example, school system A might receive a treatment (new computers) while school system B gets no new treatment. Even though there is an I.V. (compute
