Final answer:
Efficacy studies assess if an intervention works under ideal conditions often using randomized controlled trials, while effectiveness studies evaluate real-world outcomes of the intervention. Efficacy focuses on internal validity, whereas effectiveness reflects external applicability.
Step-by-step explanation:
The terms efficacy and effectiveness relate to studies evaluating the success of health interventions, such as drug treatments and public health policies.
Efficacy studies are often conducted in controlled, ideal environments, such as clinical trials, to determine if a treatment works under best-case scenarios. They typically involve randomized controlled trials (RCTs) with strict inclusion criteria, focusing on internal validity. For example, in a phase III clinical trial, a new medication's efficacy is assessed by giving it to a group of patients and comparing the outcomes to those of a control group that did not receive the treatment.
Conversely, effectiveness studies look at how well a treatment or intervention works in real-world conditions. They assess the success of programs by comparing populations with and without the intervention, taking into account various external factors. These studies can involve observational methods and consider the practical deployment of treatments to diverse populations. An example would be evaluating conservation strategies by comparing areas with and without specific conservation efforts.
Thus, while efficacy studies focus on whether an intervention can work under ideal conditions, effectiveness studies examine the real-world impact of the intervention when implemented in typical conditions.