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.
They may sometimes also include analytic work (comparing factors ââ see below). An analytic study attempts to quantify the relationship between two factors, that is, the effect of an intervention (I) or exposure (E) on an outcome (O).hey may sometimes also include analytic work (comparing factors ââ see below). An analytic study attempts to quantify the relationship between two factors, that is, the effect of an intervention (I) or exposure (E) on an outcome (O).