What is the difference between a between-subjects design and a within-subject design? Which t-test is used for each design? Provide a real- life example of a between-subjects design and a within-subjects design.

Question
Study design
asked 2020-11-09
What is the difference between a between-subjects design and a within-subject design? Which t-test is used for each design? Provide a real- life example of a between-subjects design and a within-subjects design.

Answers (1)

2020-11-10
Step 1
In between-subjects or between-groups study design, different people test each condition, so that each person is only exposed to a single user interface.
In within-subjects or repeated-measures study design, all the participants of the study tests all the conditions, that is, all the user interfaces.
In between-subjects study design, it is compared that which group is better than other, that is, both the groups are independent of each other. So, the two independent samples t-test is appropriate to use.
In within-subjects study design, the paired t-test is appropriate as all the participants are going through all the conditions making it the paired or matched samples.
Step 2
Example: A researcher wants to compare two flavors of soda, A and B, based on the ratings of how participants liked the flavors.
Between-subjects study design: The participants are randomly assigned to one of the two groups and they will be provided with either flavor A or flavor B soda.
Within-subjects study design: Each participant in the study tested both the flavors and then could tell which one they liked.
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