An investigator designs an experiment to see the effect of illumination level and duration of visual signal on detectability of change in illumination in a dark room on 120 randomly selected sample of college going male students. She decided to use low and high levels of illumination and three levels of duration of stimulus as 30,50 and 70 milliseconds through an electric chronoscopic instrument. The investigator used separate group design for various combination of treatments. These participants were required to press a 'Yes' button if they detect the signal or 'No' button if they do not. Each participant was given a total of 50 trials within which 10 signals were randomly presented. Proportions of hits and false alarms was computed for each participant and were analysed to get answers to research questions.
Identifying the Experimental Design
The experiment investigates the impact of two independent variables simultaneously:
- Illumination Level (Low, High)
- Duration of Stimulus (30ms, 50ms, 70ms)
Since the study involves more than one independent variable (factor), it is classified as a multifactor experiment.
Design Classification
The investigator used a separate group design for the various combinations of treatments. This means different participants were assigned to different treatment combinations (e.g., one group might experience low illumination and 30ms duration, while another group experiences high illumination and 50ms duration).
A design with multiple independent variables is termed a multifactor design. The use of separate groups for each combination further supports this classification, distinguishing it from a repeated measures design where the same participants would experience all conditions.
Therefore, the experimental design used is a Multifactor design.
Important Questions from Research Design
Design used in experimental research in which groups are randomly formed and that controls most sources of invalidity is known as
‘Which of the following are the complete experimental research designs?
(A) Factorial design
(B) One group after-only design
(C) Before-after design with one experiment and two control groups
(D) Latin square design
(E) One-group before-after design
Choose the correct answer from the options given below:
The 'Age' of a respondent is an example of
The internal validity factor in research is related to the issue of
The post-test only control group design avoids:
