A clinical researcher wants to compare patient outcomes from a new practice guideline vs existing… Patients will be blindly assigned… Which research method should be used?

The pretest-posttest design involves measuring outcomes before and after an intervention within the same group. While this method can show changes over time, it does not control for confounding variables or allow for comparison against a control group, which is essential for evaluating the effectiveness of a new guideline versus an existing one.

A cross-sectional study examines data from a population at one specific point in time. This method provides a snapshot of outcomes but does not allow for the assessment of causal relationships or the impact of the new guideline over time. Therefore, it is unsuitable for evaluating the outcomes of different practice guidelines.

The time-series design involves repeated observations of the same group over time, which can help identify trends before and after an intervention. However, it does not provide the same level of control as an RCT, making it less effective for comparing outcomes between two distinct practice guidelines.