Which of the following are informal experimental designs? A. Factorial design…
2024
Which of the following are informal experimental designs?
A. Factorial design
B. Before-and-after design without a control group
C. After-only design with a control group
D. Randomized block design
E. Before-and-after design with a control group
Choose the correct combination:
Answer: D. B, C and E only — ConceptExperimental designs may be grouped as informal or formal according to the degree of control and statistical structure used. Informal designs generally…
- A.
A, C and D only
- B.
B and C only
- C.
D and E only
- D.
B, C and E only
Show answer & explanation
Correct answer: D
Concept
Experimental designs may be grouped as informal or formal according to the degree of control and statistical structure used. Informal designs generally estimate an effect through simple before/after or treatment/control differences, whereas formal designs use planned randomization and more precise statistical procedures.
Application
B measures one group before and after treatment without a separate control group.
C compares a treated group with a control group only after treatment.
E measures both treated and control groups before and after treatment.
Contrast
A factorial design is formal because it systematically studies the effects and interactions of two or more factors.
D is formal because a randomized block design controls known variation through blocks and random allocation.
Result
The informal designs are B, C and E; therefore, the accepted combination is B, C and E only.