Table 3.

Clinical Research Design Advantages and Disadvantages

Design	Advantages	Disadvantages	Other considerations
Randomized control trial	Strongest causal inference	High potential for contamination/diffusion of intervention if conducted on single ICUs or in a setting where nurses rotate among different ICUs. Difficulty in achieving equality/comparability between ICUs (groups).	Could include a larger number of ICUs and/or multiple hospitals. Training a larger group of nurses (all unit staff) presents problems in intervention fidelity monitoring and potential variation in “dose”. Expensive
One Group Repeated Treatment design	Each patient is used as his/her own control. Sample size (nurses and patients) required may be smaller.	Changes can be attributed to patients’ improved conditions or acclimation over time. Patients may not remain intubated and nonspeaking long enough for all conditions to be implemented. High risk for diffusion of the intervention.
One Group Pretest-Posttest	Simple, efficient when access to experimental population is limited	Usually used to test a single intervention. Unable to examine stability of behaviors within individuals and/or group. Threats to validity include history, maturation.	Pre and post-test samples are not independent.
Sequential cohort design	Can use two or three independent groups; Intervention and nonintervention groups remain separate.	History is the main threat to validity;	Total study time and time to comparative analysis may be lengthy.