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.
Epidemiologic case-control studies are used to identify factors that may contribute to a medical condition. Epidemiological studies are categorized as either descriptive or analytic. This course describes the main elements of descriptive and analytic epidemiology and their associated study types briefly and clearly.