CAMPBELL

1
CAMPBELLS AND STANLEYS SYMBOLIC REPRESENTATION
OF TRUE EXPERIMENTS

• RO1 X O2
• RO3 O4
• Campbell, D. T. and Stanley, J (1963)
  Experimental and Quasi-experimental Designs for
  Research on Teaching. Boston Houghton Mifflin
  Co.

2
CAMPBELLS AND STANLEYS NOTATION
X represents the exposure of a group to an
experimental variable or event, the effects of
which are to be measured. O refers to the process
of observation or measurement. Xs and Os in a
given row are applied to the same persons. Left
to right order indicates temporal sequence. Xs
and Os vertical to one another are
simultaneous. R indicates random assignment to
separate treatment groups. Parallel rows
unseparated by dashes represent comparison groups
equated by randomization, while those separated
by a dashed line represent groups not equated by
random assignment.