The design diagramed below

$R=$ random assignment; $O=$ observation $($pre or posttest$)$; and $x=$ experimental stimulus or treatmen

$RO1O2$

$R,O3,O4$

R $x$ Os$.$

R $,O6$

$q,$

treats $O$ as the new study technique

is a static$-$group comparison design

is a classical experimental design

treats $O$ as the old study technique

$$ is a Solomon design