Before-after control impact design

Baseline monitoring can be combined with a before-after design, where data are collected both before and after treatment and thus replicated in time rather than space [11]. A before-after control-impact (BACI) design is often used. The control site is evaluated over a period and compared to the monitoring of the treatment site. A BACI design allows temporal variabilities in the control and treatment site to be compared. 

Before-after-control-impact (BACI) design... 

The methods for controlling sulfur oxides from coal, which, in turn, impact the combustion system design can be classified into three types (1) sulfur removal after combustion, (2) sulfur removal during combustion, and (3) sulfur removal before combustion. 

Double diffetetice or di ference-in-dififereiices method is another estimation method that can be used with experimental, quasi-experimental, and nonexperimental designs. Impact is estimated by comparing the outcomes for the treatment and the comparison groups (first difference) before and after the intervention (second difference). This method requires baseline and follow-up data from the same treatment and control groups, ideally as panel data. If the samples for the follow-up survey differ from the baseline survey, they should be from the same geographic clusters or strata in terms of some other variable. 

---