Which research design studies the effects of a program on an individual after establishing a baseline?

The choice of single-subject design as the correct answer highlights its focus on evaluating an individual's response to an intervention or program after establishing a baseline measurement. This research design involves observing and measuring the same individual under different conditions, allowing for a detailed examination of how the program impacts that specific individual over time.

In single-subject design, the established baseline serves as a comparison point to assess any changes in behavior or outcomes that occur after the implementation of the intervention. This design is particularly useful in fields such as education and psychology, where understanding the nuances of individual behavior and responses to interventions is crucial. It emphasizes the variability of individual responses rather than averaging data across groups, providing more tailored insights into the effectiveness of a program.

Longitudinal design involves repeated observations of the same subjects over an extended period, which can include measuring groups rather than individuals specifically focused on the effects of an intervention. Cross-sectional research examines data at a single point in time across different subjects, which does not track changes in individuals following a baseline. Meta-analysis, on the other hand, synthesizes results from multiple studies to derive overall conclusions rather than focusing on individual effects within a single program context.