Which design is characterized by repeated measurements of the same dependent variable over time or across conditions?

• A. Group Designs
• B. Quasi-Experimental Designs
• C. Single Subject Research Designs
• D. Qualitative Research Designs

Answer: (C)

The idea being tested is designs that repeatedly measure the same dependent variable on the same subject over time or across different conditions. This repeated-measures, within-subject approach is the hallmark of single-subject research designs. In these designs, data are collected for the same individual across successive phases—baseline and intervention—so you can observe how the dependent variable changes as the independent variable is manipulated. Because the same subject provides all the data, changes are more clearly linked to the treatment rather than to differences between groups. Common patterns include reversal designs, where the intervention is turned on and off to see if the behavior returns to baseline, and multiple-baseline designs, where the intervention is introduced at different times for different behaviors or settings. Other designs compare groups rather than repeatedly measuring the same subject, such as group designs; quasi-experimental designs involve group comparisons without full randomization; qualitative designs focus on descriptive data rather than repeated quantitative measurements of the same variable.