Experimental designs Between Withinsubjects l Betweensubjects design l

Experimental designs

Between- / Within-subjects l Between-subjects design l l l Each partcipant takes part in 1 experimental condition Analysis of differences between groups of participants from different conditions Within-subjects design l l Subjects take part in all conditions Analysis of differences of results from same participants over different conditions

Experimental research as conclusive research Conclusive Research Descriptive Causal Experimentation Field Experiments Laboratory Experiments

Preexperimental designs l One-Group After-Only l One-Group Before-After l Nonequivalent posttest-only

Validity in experimentation l Internal validity l l l Is effect CAUSED by manipulation of independent variable? Rival hypothesis / extraneous variables External validity l Generalization beyond experimental situation

Randomized Two-Group Design

Before-After Two Group Design

Solomon Four-Group Design

2 2 Factorial Design

Repeated Measures

Static-Group Comparison Design

Pretest-Posttest Nonequivalent Control Group Design

Regression-Discontinuity Design

One-Group Pretest-Posttest Design

Interrupted Time-Series Design

Replicated Interrupted Time-Series Design

Laboratory versus Field experiments Environ ment LAB Artif ici al FIEL D Real ist ic Control High Low Reactive error High Low Demand artifac ts High Low