What is causal designs
Causal research is most appropriate when research objectives include need to understand the reasons why certain market phenomena happen as they do. To measure this however, the data should be gathered under controlled conditions - which is, holding constant or neutralizing the effect of, all variables other than causation variable (in the case above packaging change). After neutralizing effects of other variables researchers manipulate the causation variable and measure change in the effect variable (in case above supermarket sales). Manipulation of the presumed causal variable and control of other related variables are distinct features of causal design.