Question

What is the difference between a Within Subjects Design and a Between Subjects Design and (b) Which type of design are we using if we must use a Dependent Samples t-test?

Answer 1

Difference between Within Subjects Design and a Between Subjects Design is that the within subjects design include dependent variable, i.e. one sample is used for testing all the conditions whereas the between subjects design include independent variables, i.e. different samples are used for testing different conditions.

so, for a dependent sample t test, we must use within subjects design because this design uses only one sample, i.e. single dependent sample for testing different conditions.