Study Groups
How volunteers are organized into groups
The way groups are arranged shapes what a study can compare and conclude.
- 01
Parallel Groups
Each group follows one path from start to finish, side by side, and results are compared at the end.
- Simple to explain
- Groups run at the same time
- Common in randomized studies
- 02
Crossover Design
Each volunteer tries more than one approach in sequence, acting as their own comparison.
- Fewer volunteers needed
- Uses a washout period
- Best for stable, long-term situations
- 03
Factorial Design
Two or more questions are tested at once by combining approaches across several groups.
- Answers multiple questions
- Efficient use of volunteers
- Can reveal interactions
- 04
Single-Arm Studies
Everyone follows the same path with no internal comparison group, often in early exploratory research.
- No comparison arm
- Often early stage
- Results need careful context