experimental research design

experimental research design

-A scientific method used to test cause-and-effect relationships.

- Refers to the complete sequence of steps that you follow in order to answer the research problem.

manipulation of variable

The researcher intentionally changes the Independent Variable (IV).

control of variables

-   Other variables are controlled/held constant to avoid affecting the results.

control group

-does not receive treatment; baseline.

experimental group

receives the treatment or intervention.

random assignment

-Participants or samples are randomly placed into groups to reduce bias.

measurement of effect

The effect of the IV on the DV is observed or measured.

independent variable

-The variable that the researcher manipulates.

dependent variable

-The variable that is measured or observed.

controlled variables

-Factors kept the same in all conditions to avoid influencing the DV.

treatment/ intervention

-The specific change applied to the IV.

replacation

-Repeating the experiment to ensure reliability.

true experimental design

Most powerful and most controlled.
Require random assignment.

1. Pretest-Posttest Control Group Design

2. Posttest-Only Control Group Design

3. Solomon Four-Group Design

quasi-experimental design

Used when random assignment is not possible.
Less control but still manipulate the IV.

1. Nonequivalent Control Group Design

2. Time-Series Design

3. Counterbalanced Design

pre-experimental design

Weak designs; no control group or randomization.

1. One-Shot Case Study

2. One-Group Pretest-Posttest Design

R, O1, O2, X

Legend of the Procedures

stands for random selection

stands for pretest

stands for posttest

stands for intervention

variation

The different types of experimental designs that researchers can choose from depending on the needs of their study.

randomization

Assigning participants or subjects to different groups (such as control and experimental groups) purely by chance—not by choice, preference, or pattern.

blocking

A process of grouping participants (or experimental units) into subgroups called “blocks” based on characteristics that might affect the results, before randomly assigning them to treatment groups.

replication

Repeating the experiment or repeating the treatment on multiple subjects to confirm that the results are reliable, consistent, and not due to chance.