Classic experimental design

Example:  food aversion therapy

Pygmalion in the Classroom:
Gains in IQ points, by grade

Solomon 4-group design

Solomon 4-group design
(hypothetical)

Contrasted groups design
(Babbie:  nonequivalent control groups)

Contrasted groups design
(Babbie:  nonequivalent control groups)

Time-series design

Control-series design
(Babbie: multiple time series)