option d. Use of a baseline measure of DV is correct. All of the listed options are shared by both single-subject designs and interrupted time-series designs, making it tricky to choose the best answer. However, depending on the specific emphasis, there is a more compelling choice:
Here's why:
a. The use of robust statistical methods: While both designs can utilize robust statistical methods to analyze data, it's not a defining characteristic unique to them. Other research designs also employ such methods.
b. The degree of focus on individual participants: Both designs focus on individual participants, but single-subject designs do so inherently, while interrupted time-series designs can sometimes involve multiple individuals observed repeatedly over time.
c. Focus on small sample sizes: Both designs often use small sample sizes due to their nature, but it's not a defining characteristic either. Other research designs can also have small samples for various reasons.
d. Use of a baseline measure of DV: This is a crucial element shared by both single-subject and interrupted time-series designs. Establishing a baseline measurement of the dependent variable before introducing the intervention or change is essential for both designs to assess the impact of the manipulation.
option d. Use of a baseline measure of DV is correct