Which research design allows the same group to be compared over time by considering the trend before and after manipulation?

Which research design allows the same group to be compared over time by considering the trend before and after manipulation?

• A. Interrupted time-series designs
• B. Longitudinal study
• C. Cross-sectional design
• D. Case study

Answer: (A)

This design focuses on detecting the effect of an intervention by looking at how a outcome changes over time within the same group. Data are collected repeatedly before and after the manipulation, so you can see whether there is a shift in the immediate level and/or a change in the ongoing trend after the intervention. This is what lets you attribute changes to the manipulation rather than to other factors, because you’re directly comparing the trajectory before with the trajectory after, within the same subjects or units. For example, if a new teaching method is introduced, you’d measure performance at multiple points before and after the change to see if scores jump or begin to rise more steeply after the method is implemented. In contrast, a longitudinal study simply follows the same group over time without necessarily introducing a deliberate interruption to assess causality; a cross-sectional design captures data at one point in time and cannot examine before/after trends; a case study involves in-depth analysis of a single case or small number of cases and isn’t designed to test an intervention with a time series.

This design focuses on detecting the effect of an intervention by looking at how a outcome changes over time within the same group. Data are collected repeatedly before and after the manipulation, so you can see whether there is a shift in the immediate level and/or a change in the ongoing trend after the intervention.

This is what lets you attribute changes to the manipulation rather than to other factors, because you’re directly comparing the trajectory before with the trajectory after, within the same subjects or units. For example, if a new teaching method is introduced, you’d measure performance at multiple points before and after the change to see if scores jump or begin to rise more steeply after the method is implemented.

In contrast, a longitudinal study simply follows the same group over time without necessarily introducing a deliberate interruption to assess causality; a cross-sectional design captures data at one point in time and cannot examine before/after trends; a case study involves in-depth analysis of a single case or small number of cases and isn’t designed to test an intervention with a time series.