P = The general population
U1 = An unrandomized  experimental group
U2 = An unrandomized control group
X = The intervention (the independent variable)
O1 = The post-intervention observation of the experimental group (the dependent variable)
O2 = The post-intervention observation of the control group

Type:

Pre-experimental Research Design

What it is:

The static group comparison design is similar to the single shot study but adds a control group to provide a control for comparison. In this design, two unrandomized groups are arbitrarily selected from the general population. One is designated as the experimental group and the other as the control group. An intervention is administered to the experimental group and then both groups are observed and recorded.

Type:

Pre-experimental Research Design

Method:

Step One

Choose two arbitrary groups from the general population "P", designate one group as the experimental group "U1", the other as the control group "U2".

Step Two

Administer the intervention "X" to the experimental group "U1".

Step Three

Observe and record both groups "O1" & "O2"

Step Four

Summarize, analyze, and report the results.

Threats to Validity

History

History is now controlled since both groups are exposed to the same external effects.

Maturation

Maturation effects can be a factor if the group observations are not coincidental.

Testing Effects

Not a factor in single test designs.

Instrumentation

Probably negligible. Depends on the method selected.

Statistical Regression

Not a factor in single test designs.

Selection

Makeup of unrandomized group capable of effecting results

Attrition

Attrition effects are uncontrolled and present a threat similar to the Type I design.

Interaction

Must always be considered.

—By Douglas E. Greathouse, MA. (2007)