quasi-experimental research design

1. Quasi-experimental design
• When individuals are not random assigned, the experimental
design is known as a quasi-experimental design
WHAT
WHEN
It’s not possible for investigators to undertake true experiments,
e.g. in random assignation of participants to control or experimental
groups

2. Quasi-experiment design
o Non-equivalent (Pretest and Post-test) Control-Group Design
o Single-Group Interrupted Time-Series Design
o Control-Group Interrupted Time-Series Design
Variations (HOW)

3. Quasi-experiment design
In this design, the experimental Group A and the control
Group B are selected with random assignment. Both groups
take a pre-test and post-test. But only the experimental group
receives the treatment.
Group A O------- X ------O
Group B O----------------O
Variations
Non-equivalent (Pretest and Post-test) Control-Group Design

4. Quasi-experimental design
In this design, the researcher records measure for a single
group both before and after a treatment.
Group A O------O------O------O------- X ------O-----O-----O------O
Variations
Single-Group Interrupted Time-Series Design

5. Quasi-experiment design
This is a modification of Single-Group Interrupted Time-Series Design
in which two groups of participants, not randomly assigned, are
observed over time. A treatment is administered to one of the group (i.e.
group A)
Group A O------O------O------O------- X ------O-----O-----O------O
Group B O------O------O------O------- O------O-----O-----O------O
Variations
Control-Group Interrupted Time-Series Design