Acres to Hectares Conversion. There are 0.404685642 hectares in an acre. In other words, it is about 40 percent of a hectare. To find out how many hectares in acres, multiply by the conversion factor or instead, use the converter below. Acre is an imperial and US customary area measurement unit which equals to 43560 square feet.
intervention study. testing an hypothesized epidemiological cause-effect relationship by intervening in a population and modifying a supposed causal factor and measuring the effect of the change.
Types of clinical trials. 1  Observational: Type of a trial in which enrolled participants are observed. Outcome measures, such as measures of strength or function may be part of the observation. 2  Interventional: A type of trial in which exposure to the potential therapy being tested, such as a drug, is assigned.