Experimental designs

Between- / Within-subjects

Between-subjects design Each partcipant takes part in 1 experimental

condition Analysis of differences between groups of

participants from different conditions Within-subjects design

Subjects take part in all conditions Analysis of differences of results from same

participants over different conditions

Experimental research as conclusive research

ConclusiveResearch

Descriptive Causal

Experimentation

Field Experiments

LaboratoryExperiments

Preexperimental designs

One-Group After-Only

One-Group Before-After

Nonequivalent posttest-only

X Y

X Y2Y1

X Y1

Y2

Validity in experimentation

Internal validity Is effect CAUSED by manipulation of independent

variable? Rival hypothesis / extraneous variables

External validity Generalization beyond experimental situation

Randomized Two-Group Design

X1

X2

Y1

Y2

R

Before-After Two Group Design

X1

X2

Y12

Y22

R

Y11

Y21

Solomon Four-Group Design

X1

X2

Y12

Y22

R

Y11

Y21

X1

X2

Y32

Y42

22 Factorial Design

X11

X11

Y1

Y2

RX12

X12

Y3

Y4

X21

X22

X21

X22

Repeated Measures

X1 Y11 Y12

R

X2

Y21 Y22X2 X1

Static-Group Comparison Design

X

not X

Y1

Y2

X1

X2

Y1

Y2

X3 Y3

Pretest-Posttest Nonequivalent Control Group Design

X1 Y2

Y4

Y1

Y3

X1

X2

Y1

Y2

X3 Y3

Y1

Y2

Y3

Regression-Discontinuity Design

X1 Y1

Y2

Y1

Y2

One-Group Pretest-Posttest Design

X Y2Y1

Interrupted Time-Series Design

X1 Y5Y2 Y4Y1 Y3 Y6

X1 Y6Y2 Y5Y1 Y4 X2Y3

Replicated Interrupted Time-Series Design

X1 Y15Y12 Y14Y11 Y13 Y16

Y25Y22 Y24Y21 Y23 Y26

X1 Y15Y12 Y14Y11 Y13 Y16

Y25Y22 Y24Y21 Y23 Y26X1

Laboratory versus Field experiments

LAB FIELD

Environment Artificial Realistic

Control High Low

Reactive error High Low

Demand artifacts High Low

Internal validity High Low

External validity Low High

Time Short Long