You cannot measure
statistical significance without random
assignment to control group and treatment group(s).
The random assignment of individual subjects to comparison groups;
The extent to which the independent variable can be manipulated by the researcher;
The time when the observations or measurements of the dependent variable occur; and
Which groups are measured and how.
Group: The portion of a sample
or population that is exposed to a manipulation of the independent
known as the treatment group.
For example, youth who enroll and participate in recreation programs are the treatment group, and the group to which no recreation services are provided constitutes the control group. Is this a true experiment?
are two primary criteria for evaluating the
validity of an experimental design.
validity. Did the treatment make a difference within yout sample?
validity, If so, is it likely to do the same throughout the
Conditions that may confuse the effect of the independent variable with that of some other variable(s).